Noninvasive evaluation of hand circulation before radial artery harvest for coronary artery bypass grafting

Systolic finger pressures during an Allen test before hemodialysis access construction predict severe postoperative hand ischemia

OBJECTIVE

The Allen Test is a simple bedside method for determining hand perfusion. Earlier studies in hemodialysis (HD) patients found that an Allen Test before access construction did not predict hand ischemia later on. The study aimed to assess whether an Allen test combined with finger plethysmography before access surgery has a potential to predict the onset of severe hemodialysis access induced distal ischemia (HAIDI).

METHODS

Prior to the first access construction in chronic kidney disease (CKD) patients, systolic finger pressures (Pdig, mmHg) were obtained using plethysmography at rest and following serial compression of the radial and ulnar artery. A drop in Pdig (∂Pdig) was calculated as the difference between Pdig-rest and Pdig-compression. Severity of postoperative HAIDI was graded as suggested by a 2016 consensus meeting. Patients with a severe type of HAIDI (grade 2b-4, intolerable pain, invasive treatment required) were compared with controls not having HAIDI.

RESULTS

A total of 105 CKD patients (age 70 ±13, 65% males) receiving their first access between January 2009 and December 2018 in one center fulfilled study criteria. Ten patients (10%) developed severe HAIDI 14 ±5 months after access construction. Prior to access creation, all HAIDI patients demonstrated a radial or ulnar dominant hand perfusion pattern compared to just 57% in controls (p=.010). Compression resulted in an almost two-fold greater ∂Pdig in patients with severe HAIDI (51 ±8 mm Hg vs. 27 ±3 mm Hg, p=.005). A 40 mm Hg ∂Pdig cut-off value demonstrated optimal tests characteristics, (sensitivity 80%, specificity 77%, PPV 27%, NPV 97%) indicating a 10 times greater risk of developing severe HAIDI.

CONCLUSIONS

Finger plethysmography quantifying ∂Pdig during an Allen test prior to access creation may identify patients who have a substantially increased risk of developing severe hand ischemia following hemodialysis access surgery.

The Use of Radial Artery for CABG: An Update

We used the radial artery as a second target conduit for coronary artery bypass grafting since 1971. However, randomized clinical studies have demonstrated differences in clinical outcomes between the radial artery and other grafts because these trials are underpowered. As we proceed toward 50 years of experience with radial artery grafting, we examined the literature to define the best second-best target vessel for coronary artery bypass grafting. The literature was reviewed with emphasis, and a large number of randomized controlled trials, propensity-matched observational series, and meta-analyses were identified with a large patient population who received arterial conduit and saphenous vein grafts. The radial artery has been shown to be effective and safe when used as a second target conduit for coronary artery bypass grafting. Results and patency rates were superior to those for saphenous vein grafting. It has also been shown that the radial artery is a safe and effective graft as a third conduit into the territory of the artery right coronary artery. However, there is little evidence based on a few comparable series limiting the use of the gastroepiploic artery. In its fifth decade of use, we can finally deduced that the aorto-to-coronary radial bypass graft is the conduit of choice for coronary operations after the left internal thoracic artery to the left anterior descending artery.

A preoperative modified Allen test result may be associated with long term mortality after hemodialysis access construction

BACKGROUND

The modified Allen test (MAT) is a simple bedside method determining collateral hand circulation prior to hemodialysis (HD) access surgery. Hand ischemia as reflected by low systolic finger pressures (P_dig) is associated with high mortality rates in severe kidney disease (CKD) patients. Aim of the present study was to assess a possible relation between absolute finger pressure drop (∂P_dig) during a preoperative MAT and mortality after a first HD access construction.

METHODS

P_dig (systolic pressure, mmHg) was measured using digital plethysmography following compression of radial and ulnar arteries in CKD patients just before access surgery between January 2009 and December 2018 in one center. The greatest ∂P_dig of both index fingers was used for analysis. Cardiovascular and overall mortality were assessed during the following 4 years using the ERA-EDTA classification system (codes 11, 14-16, 18, 22-26, 29). Cox regression analysis determined possible associations between ∂P_dig and mortality.

RESULTS

Complete data sets were available in 108 patients (male n = 71; age 70 years ±12; mean follow up (FU) 1.6 years ±0.1; FU index 99% ±1). Median ∂P_dig was 31 mmHg (range 0-167 mmHg). Patients having cardiovascular disease (CV+) demonstrated higher ∂P_dig values (CV+ 44 ± 5 mmHg vs CV- 29 ± 3 mmHg, p = 0.012). A total of 26 patients (24%) died during FU (CV+ death, n = 16; 62%). For each 10 mmHg ∂P_dig increase, overall mortality increased by 10%, and CV+ mortality by 15% (overall mortality: HR 1.10 [1.01-1.22], p = 0.048; CV+ mortality: 1.15 [1.03-1.29], p = 0.017). Following correction for age, ∂P_dig remained associated with CV+ mortality (HR 1.13 [1.00-1.26], p = 0.043).

CONCLUSIONS

A large drop in systolic finger pressure during a preoperative MAT is related to mortality after primary HD access surgery. The role of this potential novel risk parameter requires confirmation in a larger population.

Collateral Circulation Testing of the Hand- Is it Relevant Now? A Narrative Review

Testing for collateral circulation of the hand before any radial artery procedure has been a subject of many controversies. Neither the Allen's test (AT) nor the plethysmography based Barbeau test, adequately and reliably test for collateral circulation. With growing interest in radial approaches for vascular procedures, its common use for arterial monitoring and blood gas sampling, there has been a growing interest in the relevance of assessing collateral hand circulation. Multiple studies now refute the utility of collateral testing, yet it continues to be propagated as an essential triaging assessment tool by educators. Allen's, or modified Allen tests (MAT) are operator dependent and often subjected to observational bias. Barbeau test is more objective, however, it fails to show added benefit in assessing pre-procedural patency. Despite studies questioning the validity of collateral circulation assessment, these tests continue to preclude radial approach. There is no standardization for being considered an abnormal test across literature and the significance of an abnormal test translating into a clinical outcome has not been investigated in prior studies. This may be attributed to the robust vascular supply of the hand, connections at the digital circulation level and vessel recruitment in an event of occlusion. We reviewed this topic extensively and make an argument that non-invasive collateral testing should be abandoned as a triage tool for radial artery procedures such as arterial punctures, arterial monitoring, and transradial vascular procedures.

Prospective randomized trial of endoscopic vs open radial artery harvest for CABG: Clinical outcome, patient satisfaction, and midterm RA graft patency

BACKGROUND AND AIM

Endoscopic radial artery (RA) harvest (ERAH) is an alternative to open RA harvest (ORAH) technique. Our aim was to ascertain clinical outcomes, patent satisfaction, and 1-year angiographic patency rates after ERAH and ORAH.

PATIENTS AND METHODS

A total of 50 patients undergoing coronary artery bypass grafting were prospectively randomized to two groups. In the ERAH group (25 patients) the RA was harvested endoscopically and in the ORAH group (25 patients) openly.

RESULTS

There were not differences between the groups in preoperative characteristics. Length of skin incision was shorter in ERAH (P < .001) but there were not differences in the length of RA, harvest time, blood flow, and pulsatility index after ERAH and ORAH. Wound healing was uniformly smooth in ERAH and there were two hematomas and one infection in ORAH. Postoperatively, major neuralgias were present in five patients in ORAH and none in ERAH and minor neuralgias in 11 and 3 patients (P = .02) respectively. Twenty-four patients in ERAH and four in ORAH graded their experience as excellent (P < .001). One-year angiographic RA patency was 90% without intergroup difference. Target vessel stenosis less than 90% adversely affected RA patency (P < .0001).

CONCLUSIONS

In expert center, ERAH does not appear to have negative impact on the time harvest, the length, and quality of RA conduit, the wound healing, and the occurrence of hand and forearm complications. In addition, provides excellent cosmetic result and patient satisfaction. RA graft patency is gratifying when placed to a target coronary artery vessel with stenosis greater than 90%.

Assessment of collateral hand circulation by modified Allen's test in normal Indian subjects

BACKGROUND

Allen's test (AT) and Modified Allen's Test (MAT) are used as screening methods for assessment of the hand circulation. Few people lack the dual blood supply of hand and are at risk of hand ischemia after any intervention on radial artery. The Purpose of the study was to assess the collateral circulation of hand using MAT in normal Indian subjects and in elderly population to know the prevalence of positivity of Allen's test.

METHODS

900 participants (1800 hands) were divided in two groups. Group I had participants with age <50 years and group II had participants with age ≥50 years. MAT was performed in all participants and results were compared between the two groups.

RESULTS

In group I (n = 450, 900 hands), 313 were males and 137 were females, with mean age of 35.04 years. The relative percentages of a normal, equivocal, borderline and abnormal MAT were 77.8%, 16.6%, 3.7% and 1.6%, respectively. In group II (n = 450, 900 hands), 248 were males and 202 were females, with mean age of 60.4 years. The relative percentages of a normal, equivocal, borderline and abnormal MAT were 69.0%, 18.6%, 6.60% and 5.66%, respectively. A positive/abnormal test was significantly more common (5.66% Vs 1.66%, P < 0.00001) in older group.

CONCLUSION

MAT is simple, time tested and non invasive test to assess collateral circulation of the hand. A negative MAT safely selects patients for radial artery harvest; however, if the test is positive and in older patients then a second objective test may be needed.

Carotid artery occlusion and revascularization in the management of meningioma

As the carotid artery courses through the skull base and into the subarachnoid space, it lies in close proximity to regions notorious for meningioma growth. Although infrequent, the growth of these tumors can compromise blood flow through the artery, putting the downstream territory at risk for stroke. In other scenarios, removal of these tumors sometimes requires planning to accomplish both tumor removal and revascularization in the same procedure when then the tumor invades the artery. Since revascularization (bypass surgery) is best performed on a nonemergent basis, it should be given consideration in the preoperative setting. Crisis situations related to intraoperative iatrogenic injury are managed methodically by determining the site of vessel injury and then deciding whether a primary repair or bypass procedure is necessary. The mainstays of revascularization procedures of the carotid artery include flow augmentation and flow replacement, with the superficial temporal artery and external carotid artery being the donor sites, respectively. Although tumor control or cure can be accomplished with surgical, radiosurgical, or combined methods, attention to vascular structures and ensuring blood flow preservation as part of the treatment plan is an important tenet in meningioma surgery.

Preoperative management of arteriovenous fistula (AVF) for hemodialysis

Native arteriovenous fistula (AVF) is the favorite access for hemodialysis (HD). The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) recommends its creation in most patients with renal failure. Unfortunately, intensive efforts to promote native AVF in patients with marginal vessels have increased the rate of primary fistula failure. A non-functioning fistula prompts the use of central venous catheter (CVC) that, unlike AVF, has been associated with an increased risk of morbidity and mortality among patients receiving HD. We believe that successful and timely AVF placement relies on the development of a multidisciplinary integrated preoperative program divided into five stages: (i) management of patients with advanced chronic kidney disease (CKD), (ii) management of preoperative risk factors for AVF failure, (iii) planning of native AVF, (iv) assessment of patient eligibility and (v) preoperative vascular mapping. Focusing specifically on native AVF, we review scientific evidence regarding preoperative management of this vascular access in order to favor construction of long-term functioning fistula minimizing development of severe complications.

The Incomplete Superficial Palmar Arch

Introduction:

Superficial palmar arch (SPA) is dominant vascular structure in palm of hand. In present study we described a case of Ulnar / Radiopalmar pattern of incomplete SPA in an Iranian cadaver. When the SPA is complete, the superficial palmer branches of the radial artery contribute to the ulnar artery. In incomplete type of SPA, there was no anastomosis between the ulnar and radial arteries (UA, RA).

Case Report:

In the present case, the brachial artery divided into RA and UA at the cubital fossa. There was no anastomosis between radial and ulnar arteries (RA, UA) in the palm of the hand. UA gave three palmar digital arteries; proper palmar digital artery and two common palmar digital arteries. RA gave proper palmar digital artery and arteria princeps pollicis.

Conclusion:

Knowledge of anatomical variation of SPA is important for the hand surgical interventions and this is a very rare variation which can be easily tested clinically by Allen's test

Radial artery occlusion after transradial approach to cardiac catheterization

Radial artery occlusion (RAO) is the most common complication of the transradial approach (TRA) to cardiac catheterization, with a reported incidence between 0.8 % and 30 %. RAO is likely the result of acute thrombus formation and complicated by neointimal hyperplasia. Most RAO are asymptomatic with rare cases of acute hand or digit ischemia reported in the literature. The role of testing for dual circulation to the hand in determining the safety of TRA as it relates to symptomatic RAO is controversial; however, modifiable risk factors like low sheath-to-artery ratio, adequate anticoagulation, and non-occlusive ("patent") hemostasis are likely to prevent RAO. This review examines the incidence of RAO, potential mechanisms leading to RAO, and strategies to prevent and treat RAO.

Is radial artery Doppler scanning mandatory for use as coronary bypass conduit?

BACKGROUND

Screening of the radial artery prior to harvesting as a conduit for coronary bypass may be performed clinically by the Allen test or by Doppler ultrasound. In a developing country like ours, the use of resources for Doppler studies may be questioned when Allen tests lead to a low rate of clinical sequelae. However, the rare occurrence of hand ischemia may be devastating and could justify the routine use of Doppler screening. This study aimed to address this question.

METHODS

One hundred patients undergoing elective coronary artery bypass grafting were screened by the modified Allen test and Doppler ultrasound for suitability of use of a radial artery conduit. After harvesting, proximal and distal segments of the radial artery were subjected to histopathological examination.

RESULTS

Of the 95 patients deemed suitable for radial artery grafting, 6 had mild calcification on Doppler ultrasound and 9 had calcification on histopathological examination. While Doppler showed atherosclerosis in 9 patients, only 6 had histopathological evidence of this (false-positive rate 3%). Of the 6 patients with histopathologic evidence of atherosclerosis, 2 were negative on Doppler (false-negative rate 2%).

CONCLUSION

Routine preoperative Doppler screening of the radial artery in the setting of limited resources is not justified. On the other hand, the time-tested Allen test which is easy to perform, interpret, and reproduce can be safely used as the sole screening test to harvest the radial artery.

Palmar arch anatomy: Ajmer Working Group classification

Introduction

Forearm arteries are frequently used as workhorse site for cardiac catheterization, bypass grafting and haemodialysis access. There is paucity of data on palmar circulation in live human being and only cadaveric data are available till date. We, therefore, made an attempt to look at the various patterns of sufficient or insufficient palmar arch circulation and various anomalies of forearm arteries, to discuss their clinical implications.

Methods and results

We obtained the forearm and hand arteriograms of patients (n = 302) through radial (n = 200) and ulnar routes (n = 102). Modified Allen’s test was normal in all of our patients. On the basis of predetermined parameters angiograms were analysed and findings were divided into three groups. These three groups were further classified as type A, type B, type C superficial palmar arch.

Conclusion

We concluded that type A superficial palmar arch is most suitable for providing adequate collateral circulation in case of harvesting of forearm vessel, whereas type C superficial palmar arch appears to be highly susceptible for digital ischemia in case of radial or ulnar artery occlusion. Modified Allen’s test alone is not justifiable for documenting good collateral circulation and it should be supplemented by other tests to document good collateral circulation before proceeding to any radical procedure.

Complications related to radial artery occlusion, radial artery harvest, and arterial lines

Recent publications have suggested that there may be an important role for the radial artery regarding long-term perfusion of the hand. The increasing popularity of the radial artery as an access site for cardiac catheterization has also resulted in the recognition of acute and chronic radial artery occlusion, and cardiologists have placed renewed emphasis on preserving the patency of this artery for future interventional procedures. This article reviews the present literature on radial artery harvest and occlusion. Also discussed are the complications associated with radial artery occlusion and treatment options to prevent such complications.

Effects of skeletonized versus pedicled radial artery on postoperative graft patency and flow

Background

Radial artery (RA) was the second arterial graft introduced in clinical practice for myocardial revascularization. The skeletonization technique of the left internal thoracic artery (LITA) may actually change the graft's flow capacity with potential advantages. This leads to the assumption that the behavior of the RA, as a coronary graft, is similar to that of the LITA, when skeletonized.

Objective

This study evaluated 'free' aortic-coronary radial artery (RA) grafts, whether skeletonized or with adjacent tissues.

Methods

A prospective randomized study comparing 40 patients distributed into two groups was conducted. In group I, we used skeletonized radial arteries (20 patients), and in group II, we used radial arteries with adjacent tissues (20 patients). After the surgical procedure, patients underwent flow velocity measurements.

Results

The main surgical variables were: RA internal diameter, RA length, and free blood flow in the radial artery. The mean RA graft diameters as calculated using quantitative angiography in the immediate postoperative period were similar, as well as the flow velocity measurement variables. On the other hand, coronary cineangiography showed the presence of occlusion in one RA graft and stenosis in five RA grafts in GII, while GI presented stenosis in only one RA graft (p = 0.045).

Conclusion

These results show that the morphological and pathological features, as well as the hemodynamic performance of the free radial artery grafts, whether prepared in a skeletonized manner or with adjacent tissues, are similar. However, a larger number of non-obstructive lesions may be observed when RA is prepared with adjacent tissues.

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.

Assessment of collateral circulation to the hand prior to radial artery harvest

Assessment of collateral circulation to the hand is required prior to invasive procedures or harvesting of the radial artery (RA). A modified Allen’s test (MAT) is commonly used to assess palmar arch collaterals. A variety of non-invasive methods including digital pressures, plethysmography, pulse oximetry and duplex ultrasonography are available to supplement physical examination. However, no consensus exists about the proper role of the MAT and the most appropriate non-invasive test (NIT) in this situation. Interpretation of the MAT and NIT findings are also controversial. This paper reviews the anatomy and the physiologic basis for the MAT and various NITs, the pros and cons of various NITs and recommendations for the assessment of collateral circulation to the hand prior to interventions directed at the RA.

Prevalence, risk factors, and clinical correlates of ulnar artery occlusion in the general population

BACKGROUND

Occlusion of the ulnar artery is found in a substantial proportion of elderly patients. The aim of this study was to estimate the prevalence of ulnar artery occlusion in a sample of the general population of France, look for its risk factors, and evaluate its clinical correlates.

METHODS

This study was an offshoot of a cross-sectional epidemiologic study in the general population of four locations in France (Tarentaise, Grenoble, Nyons, and Toulon). In phase I, random samples of 2000 individuals per location aged >or=18 years old were interviewed by phone for screening of Raynaud phenomenon. In phase II, subsamples of individuals were invited to a medical interview and physical examination where the presence of Raynaud phenomenon and occupational risk factors were recorded and a bilateral clinical Allen test was performed for the detection of ulnar artery occlusion. Phase II comprised 688 women and 335 men.

RESULTS

In 36 men and seven women, at least one occluded ulnar artery was found. The estimated prevalence was 9.6% in men and 1.0% in women (P < .001). The occluded artery was more often in the dominant hand of both men (8.1% vs 2.4%; P < .001) and women (0.9% vs 0.4%; P = .34). Ulnar artery occlusion was found more often in men aged >50 years (16.4%) than in younger men (1.4%; P < .001). Besides age, male sex, and dominant side, the only independent risk factor was an occupational exposure in men to repeated palmar trauma, with a significant quantitative relationship in the frequency of the impacts (P < .001) and the duration of the exposure (P < .001). Exposures to hand-held vibrating tools and cigarette smoking did not show a significant relationship in the multivariate analysis. Most individuals with ulnar artery occlusion did not have associated complaints; however, the diagnostic criteria for Raynaud phenomenon was validated in 13 of the 36 affected men. The association remained significant after adjusting for occupational exposure to vibrating tools. One individual reported a previous episode consistent with an attack of permanent digital ischemia.

CONCLUSION

This study confirms a substantial prevalence of ulnar artery occlusions in the general population, mostly in middle-aged and elderly men, which appears to be principally related to an occupational exposure to repeated occupational palmar trauma. Although there is a significant association with Raynaud phenomenon, most often the consequences of this occlusion remain subclinical.

Graft selection in cerebral revascularization

Cerebral revascularization constitutes an important treatment modality in the management of complex aneurysms, carotid occlusion, tumor, and moyamoya disease. Graft selection is a critical step in the planning of revascularization surgery, and depends on an understanding of graft and regional hemodynamics, accessibility, and patency rates. The goal of this review is to highlight some of these properties.

Correlation of modified allen test with Doppler ultrasonography

The feasibility of using modified Allen tests to evaluate arterial circulation in the forearm for possible radial artery grafting, and the correlation of these tests with Doppler ultrasonography, were examined. The hand circulation of 50 patients scheduled for coronary artery bypass grafting was assessed by plethysmography, pulse oximetry, and pencil Doppler, as well as Doppler ultrasonography. Flow, velocity, and diameter of the radial, ulnar, and snuffbox arteries were recorded, and radiological screening indices were evaluated to establish a standard set of criteria. The results of modified Allen tests by plethysmography and pulse oximetry demonstrated the dominance of the ulnar artery. The indices of flow x diameter and velocity x diameter, obtained from Doppler ultrasound measurements, confirmed the dominance of the ulnar artery. When compression was applied to the arteries sequentially, significant alterations were found. The arterial circulation in the forearm can be safely evaluated by the modified Allen tests with plethysmography, pulse oximetry, and pencil Doppler, as these results correlated with Doppler ultrasound.

The value of Allen's test in harvesting a radial forearm flap: correlation of ex-vivo angiography and histopathological findings

The radial forearm flap is one of the most commonly raised free flaps. In most cases an Allen's test is sufficient for preoperative assessment of the palmar arch, but an intact palmar arch does not imply that the radial artery is suitable for microvascular anastomosis. For a patient operated for oral squamous cell carcinoma, reconstruction was planned with a radial forearm flap. The flap had to be discarded because of advanced atherosclerosis in the presence of a negative Allen's test. The correlation of an ex-vivo angiography and the histopathologic findings was assessed. In cases of expected vascular disease, further examinations like color flow Doppler ultrasound are recommended to ensure sufficient perfusion of the radial artery.

Can the modified Allen's test always detect sufficient collateral flow in the hand? A computational study

Blood flow in the largest arteries of the arm up to the digital arteries is numerically modelled using the one-dimensional equations of pressure and flow wave propagation in compliant vessels. The model can be applied to different anatomies of arterial networks and can simulate compression of arteries, these allowing us to simulate the modified Allen's test (MAT) and to assess its suitability for the detection of sufficient collateral flow in the hand if radial blood supply is interrupted. The test measures blood flow in the superficial palmar arch before and during compression of the radial artery. The absence of reversal flow in the palmar arch with the compression indicates insufficient collateral flow and is referred to as a positive MAT. This study shows that small calibres of the superficial palmar arch and insufficient compression of the radial artery can lead to false-positive results. Measurement of the drop in digital systolic pressures with compression of the radial artery has proved to be a more sensitive test to predict the presence of sufficient ulnar collateral flow in networks with small calibres of the superficial palmar arch. However, this study also shows that digital pressure measurements can fail in detecting enough collateral flow if the radial artery is insufficiently compressed.

Evaluation of Allen’s test in both arms and arteries of left and right-handed people

The Allen's test as described in 1929 by Edgar V. Allen has been modified, adapted and complemented by other newer modalities but remains a first line standard test to evaluate the arterial supply of the hand. In this study an attempt has been made to add more information regarding the arterial supply of the hand, in left- and right-handed individuals, left and right hands and the ulnar and radial arteries, when doing the Allen's test. A modified Allen's test using an oxygen saturation monitor was used. The sample group consisted of 80 (30 left-handed and 50 right-handed) students. No significant differences between the Allen's test of the left and right hands in the left and right-handed individuals were found. There was a marginal but not significant difference between the two arteries. The ulnar artery took slightly longer to reach baseline values as compared to the radial artery. The results suggest that a positive Allen's test can be found in both left and right-handed people, with regard to the left and right hands and both radial and ulnar arteries may be implicated. This information should be kept in mind when selecting either the radial or ulnar artery for grafting purposes (e.g. coronary angiosurgery) and forearm artery cannulation.

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.

Vascular Communications of the Hand in Patients Being Considered for Transradial Coronary Angiography

OBJECTIVES

The purpose of this study was to assess the accuracy of the Allen's test (AT) in predicting hand ischemia in patients undergoing transradial coronary angiography.

BACKGROUND

Patients with poor vascular communications between the radial artery (RA) and ulnar artery (UA), as indicated by an abnormal AT, are usually excluded from transradial coronary angiography to avoid ischemic hand complications.

METHODS

Over a four-month period, patients undergoing coronary angiography were screened for AT time. Circulation in the RA, UA, principal artery of the thumb (PAT), and thumb capillary lactate were measured before and after 30 min of RA occlusion.

RESULTS

Fifty-five patients were studied (20 normal, 15 intermediate, 20 abnormal). Three patients with an abnormal AT were excluded, owing to absence of detectible flow in the distal UA. Patients with an abnormal AT were all men, had a larger RA (3.4 vs. 2.8 mm; p <0.001), and smaller UA (1.9 vs. 2.5 mm; p <0.001), compared with patients with a normal AT. After 30 min of RA occlusion in patients with abnormal AT, blood flow to the PAT improved (3.2 to 7.7 cm/s; p <0.001) yet remained reduced relative to patients with normal AT (7.7 vs. 21.4 cm/s; p <0.001. Thumb capillary lactate was elevated in patients with an abnormal AT (2.0 vs. 1.5 mmol/l; p = 0.019).

CONCLUSIONS

After 30 min of RA occlusion, patients with an abnormal AT showed significantly reduced blood flow to the thumb and increased thumb capillary lactate (compared with patients with a normal AT) suggestive of ischemia. Transradial cardiac catheterization should not be performed in patients with an abnormal AT.

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.

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.

Endoscopic radial artery harvesting is better than the open technique

BACKGROUND

Radial arteries are being used more often for coronary artery bypass grafting. A minimally invasive technique was devised for harvesting vessels and compared with the traditional harvesting technique.

METHODS

In a prospective study of 200 consecutive patients undergoing coronary artery bypass grafting, 100 patients had traditional open radial artery harvesting and 100 underwent endoscopic radial artery harvesting. All patients had a preoperative modified Allen's test with Doppler imaging. The traditional technique involved a longitudinal incision over the radial aspect of the arm from the wrist to the antecubital fossa. The radial artery was dissected subfascially and removed. The endoscopic technique involved a 3-cm incision over the radial aspect of the arm. A vessel loop was placed around the artery and carbon dioxide was insufflated into the wound. The radial artery was dissected to the brachial artery and ligated with an Endo-loop ligature. The branches were divided with bipolar electrocautery and ligated with clips. Patients were evaluated for postoperative pain, bleeding, neuralgias, infection, and any adverse events. A p value of less than 0.05 was considered significant.

RESULTS

All 200 radial arteries were successfully harvested and used as grafts. Patients who had undergone endoscopic radial artery harvesting had significantly fewer major complications than patients who underwent the open technique: hematomas (five versus no complications) or wound infections requiring antibiotics (seven versus one complication). The occurrence of major neuralgias that restricted function were also significantly lower postoperatively and 1, 3, and 6 months later (ten versus one, eight versus one, five versus zero, and one versus zero, respectively).

CONCLUSIONS

Endoscopic radial artery harvesting results in good cosmetic results, useable grafts, and minimal neuralgias. Endoscopic radial artery harvesting is better than traditional open radial artery harvesting.

Outcome assessment of hand function after radial artery harvesting for coronary artery bypass

The radial artery has gained widespread acceptance as a conduit for coronary artery bypass. Advantages include minimal donor site discomfort, ease of handling, excellent early patency rates, and the possibility of freedom from late conduit atherosclerosis. Although most series describe minimal morbidity, a significant incidence of radial sensory neuropathy and isolated instances of hand claudication and ischemia have been reported. We performed an outcome study utilizing the Short Form-36, the Upper Limb-Disabilities of Arm, Shoulder and Hand, and a modified self-administered hand diagram to compare 288 patients undergoing coronary artery bypass utilizing the radial artery with a control group of 174 patients undergoing coronary artery bypass without the radial artery. The data were analyzed by the t test for continuous variables and the chi-square test for categorical variables, and subsequently a multivariate regression model was constructed. No patients developed hand claudication or ischemia. Although there was an incidence of radial sensory neuropathy of 9.9% associated with radial artery harvest, it was not significantly higher than the incidence in the control group (5.2%, p =.16). Intrinsic patient factors such as obesity, age, diabetes, and peripheral vascular disease were the principal determinants of overall health and quality of life issues.

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.

Duplex ultrasonography predicts safety of radial artery harvest in the presence of an abnormal Allen test

BACKGROUND

The Allen test is commonly used to assess collateral hand circulation before radial artery harvest for coronary artery bypass grafting. However there is no consensus as to whether an abnormal Allen test is an absolute or relative contraindication to radial artery harvesting. We assessed the safety of harvesting the radial artery using arterial duplex ultrasonography in patients with an abnormal Allen test.

METHODS

Two hundred and eighty-seven consecutive patients scheduled for total arterial coronary revascularisation underwent preoperative Allen tests over a 34-month period. Patients with an abnormal Allen test underwent duplex ultrasonography preoperatively to assess the adequacy of the ulnar collateral supply and the suitability of the radial artery for harvesting.

RESULTS

Two hundred and forty-four patients (85%) had a normal left Allen test and proceeded directly to radial artery harvest. Forty-three patients (15%) with an abnormal left Allen test underwent duplex ultrasonography scans and of those, 5 patients had an abnormal scan. These patients underwent scanning of the contralateral forearm. Three patients had a normal right forearm arterial duplex scan and the right radial artery was harvested. The mean diameter of the radial and ulnar arteries was not significantly different between the patients with normal and abnormal duplex ultrasonograms. There were no ischemic hand complications in this series.

CONCLUSIONS

The Allen test is a quick, easy, and reliable screening test before radial artery harvesting in the majority of patients. Duplex ultrasonography predicts safe radial artery harvest in the majority of patients with an abnormal Allen test.

Resident research training conducted in a community hospital general surgery residency program

PURPOSE

Research is educationally important for surgical residents. However, little information exists regarding effective methods for teaching residents scientific methodology in a community hospital. This effort describes an effective program conducted in a community hospital for enhancing scientific opportunities of surgical residents.

METHODS

A strong infrastructure that supports research is necessary. Dedicated nonsalaried teaching faculty serve as mentors and co-investigators. Opportunities to engage in basic research are made available in off-campus basic science laboratories.

RESULTS

Research productivity has been prolific, as demonstrated by numerous publications. Residents interested in sub-speciality training have been able to conduct research that has made them competitive for fellowships and a wider range of practice choices.

CONCLUSION

Rigorous research can be effectively taught in a community hospital, provided adequate educational and funding support is provided and faculty actively mentor residents. Having research capabilities provides added incentive for better-qualified medical students to apply to a surgical residency position in a community hospital. Research productivity also enhances the ability to better recruit new faculty.

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.

The snuffbox technique: a reliable color Doppler method to assess hand circulation

OBJECTIVE

Although the Allen test is crude and subjective, an objective color Doppler method has yet to be established in the assessment of hand circulation before radial artery harvesting. Doppler studies so far have neglected the Doppler principle that the insonation angles should be less than 30 degrees and have not been compared with any standard except the crude Allen test. We therefore introduced the snuffbox technique, measuring the radial artery at the anatomic snuffbox, which is the most distal area after harvesting. Color Doppler methods were compared with the stump pressure as a criterion standard.

METHODS

Maximal flow velocity and Doppler angles of the snuffbox, palmar artery, and ulnar artery were measured in 20 hands before and after radial artery harvesting. Stump pressure was measured during surgery.

RESULTS

Maximal flow velocity in the snuffbox decreased with radial artery compression and after radial artery harvesting. All the flow patterns in the snuffbox technique showed simultaneous reversal. Maximal flow velocity in the ulnar artery increased with radial artery compression and after radial artery harvesting. Maximal flow velocity in the palmar artery did not change significantly with radial artery compression or after radial artery harvesting. Doppler angles were 20.9 degrees +/- 6.0 degrees in the radial artery of the snuffbox, 82.5 degrees +/- 6.1 degrees at the palmar artery, and 81.0 degrees +/- 7.6 degrees at the ulnar artery. The changes in the snuffbox technique were highly correlated with the stump pressure ratio (P <.001).

CONCLUSIONS

Among various color Doppler methods, the snuffbox technique was precise and reliable.

Association of the absence of palmaris longus tendon with an anomalous superficial palmar arch in the human hand

The normal arterial supply to the human hand is via the ulnar and radial arteries which unite mid-palm to form a complete arch called the superficial palmar arch (SPA). From the SPA blood vessels pass anteriorly to supply the thumb and digits, and deeply to complete the deep palmar arch. Previous reports have documented anomalies of the SPA formation, and this may change the normal blood distribution to the thumb and the digits. There have also been reports of the absence of the palmaris longus tendon. A total of 47 embalmed cadaveric hands (some paired, some single) were dissected and the presence of an anomalous SPA was more frequently observed when the palmaris longus tendon was absent. This may be significant when considering the suitability of patients for hand surgery which involves interruption to the vascular supply to the hand, e.g. harvesting upper limb vessels for coronary artery grafting. The current techniques for assessing the vascular supply to the hand (Aliens test and/or Doppler ultrasounding) are unreliable. Demonstration of a palmaris longus tendon in the living arm is easy and the use of this in combination with the other techniques may improve overall reliability.

Complications of invasive monitoring

Invasive monitoring in anesthesiology is relatively safe. Arterial catheterization in particular has an extremely low rate of serious complications. Radial, brachial, and femoral artery catheterization sites appear to have similar and low complication rates. CVP and PA catheters are more dangerous and entail potentially fatal complications. The most troublesome complication with CVP catheters is perforation of the heart or cava, which should be avoidable under most circumstances if care is taken to position the catheter properly, outside the heart. Chest radiography should be used to specifically ascertain that the catheter is not in a dangerous location. The most troublesome complication with PA catheters is perforation of the pulmonary artery. This is probably a sporadic problem, and it is not necessarily avoidable by adherence to particular techniques. It should be assumed that hemoptysis in a patient with a PA catheter is caused by perforation of the pulmonary artery until proven otherwise, and it should be treated aggressively.

Endoscopic radial artery harvesting: results of first 300 patients

BACKGROUND

With the expanded use of the radial artery as a bypass conduit in patients undergoing coronary artery bypass grafting, an endoscopic radial artery harvesting method was used to improve esthetics and patient acceptance, and possibly, to decrease hand neurologic complications.

METHODS

After informed consent and confirmation of adequate ulnar collateral blood flow, 300 consecutive patients undergoing coronary artery bypass grafting had their nondominant radial artery endoscopically removed through a small 3-cm incision just proximal to the radial styloid prominence. Standard endoscopic vein equipment (30-degree 5-mm endoscope, subcutaneous retractor, and vessel dissector) with ultrasonic harmonic coagulating shears were used. After radial artery isolation, the radial artery was proximally clipped and transected 1 to 2 cm distal to the visualized ulnar artery origin to the inferior end of the wrist incision.

RESULTS

The mean age was 62.2 years; 23% of the patients were women, 39% had diabetes mellitus, and 28% had peripheral vascular disease. All 300 endoscopic radial arteries were grossly acceptable and used for grafting. Early in the series, 29 patients (9.7%) required a second 3-cm incision proximally for vascular control. Only one wrist incision was required at the last 200 cases. The conduit length varied between 18 and 24 cm. Occurring early in the series, hospital complications were two tunnel hematomas requiring drainage and one brachial artery clipping repaired primarily without sequela. At 30 days postoperative follow-up, 5 patients (1.6%) had been treated with oral antibiotics for incisional cellulitis and 26 patients (8.7%) had objective dorsal thenar sensory numbness. No ischemic hand complication, perioperative myocardial infarction, reintervention in radial artery graft distribution, or numbness in the lateral forearm occurred. All patients expressed marked satisfaction with the small incision and cosmetic result.

CONCLUSIONS

In our initial experience, endoscopic radial artery harvesting can be performed safely, with minor, infrequent complications. A full-length radial artery conduit can be obtained with improved esthetics and patient satisfaction and acceptance. Late dorsal thenar paresthesias, although infrequent, continue to be a problem as with the open method.

Intraoperative confirmation of ulnar collateral blood flow during radial artery harvesting using the "squirt test"

Hand ischemia is a major concern after radial artery harvesting for coronary revascularization. Although a number of preoperative tests have been described to assess the adequacy of ulnar collateral blood flow, many of them are subjective and unreliable. In addition, the presence of arterial connections between the radial and ulnar systems in the elbow and forearm and variability in forearm angiology imply that assessment of alternative blood supply to the hand can only be made once collateral branches of the radial artery have been divided. We describe a technique for intraoperative assessment of ulnar collateral blood flow after mobilization and division of collateral branches of the radial artery.

Effect of radial artery harvest on collateral forearm blood flow and digital perfusion

BACKGROUND

Changes describing digital and forearm circulation after radial artery harvest have been reported infrequently.

METHODS

This prospective study examined digital perfusion and forearm collateral circulation preoperatively and postoperatively in patients who underwent coronary artery bypass grafting with radial artery free grafts. Noninvasive evaluation was conducted with digital photoelectric plethysmography and color flow and pulsed Doppler studies.

RESULTS

Thumb perfusion index decreased from 1.25 to 0.84 (30%, P <.001) in the unoperated extremities and from 1.23 to 0.80 (36%) in the operated extremities (P <.001). Doppler studies in extremities after radial artery harvest demonstrated an increase in ulnar artery diameter from 3.87 to 4.66 mm (15.7%, P <.001) and a rise in ulnar blood flow velocity from 38.96 to 48.46 cm/s (17.4%) preoperatively to 8 weeks postoperatively (P <.001). No hand ischemia was noted.

CONCLUSIONS

Our study identified a mild reduction in digital perfusion and an increase in ulnar artery flow velocity and diameter with no clinical sequelae or compromise in hand function after radial artery harvest in properly selected patients.