Ann Thorac Surg 2003;75:1171-1174
© 2003 The Society of Thoracic Surgeons
Original article: cardiovascular
Effects of radial artery harvesting on forearm function and blood flow
William C.F. Chong, FRCSa,
Paul J.L. Ong, MRCPb,
Christopher S. Hayward, MDb,
Peter Collins, MDb*,
Neil E. Moat, MSa
a Department of Cardiothoracic Surgery, Royal Brompton and Harefield NHS Trust, London, United Kingdom
b Cardiac Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College, London, United Kingdom
Accepted for publication November 11, 2002.
* Address reprint requests to Professor Collins, Cardiac Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College, Dovehouse St, London SW3 6LY, UK
e-mail: peter.collins{at}ic.ac.uk
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Abstract
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BACKGROUND: There is little information on the effects of radial artery harvesting on postoperative forearm function and blood flow. We evaluated the early changes in forearm neural sensation, circumference, grip power, cyclical exercise fatigue, and blood flow after radial artery harvesting for coronary artery bypass graft (CABG) surgery.
METHODS: Twenty-three patients with negative Allen’s test of the nondominant forearm were recruited preoperatively and underwent assessment of bilateral forearm function (soft touch and pin-prick neural sensation, circumference, handgrip power, cyclical exercise fatigue) and blood flow measurements (forearm plethysmography). All vasoactive drugs were stopped 24 hours before assessments. Identical follow-up assessments were conducted (mean ± SEM) 3.4 ± 0.4 months postoperatively.
RESULTS: At the time of postoperative assessment all harvested forearm wounds were healed. There was no reduction of postoperative soft touch sensation but in 3 patients objective pinprick sensation was reduced in the distribution of the lateral antebrachial cutaneous nerve of the harvested forearms. Postoperative forearm circumference (p < 0.05) and grip power (p < 0.05) were significantly reduced in both forearms, however cyclical exercise fatigue was improved in both forearms. Preoperative and postoperative forearm blood flow at rest and in exercise-induced ischemic reperfusion were not significantly different in both forearms.
CONCLUSIONS: In patients with a negative Allen’s test, harvesting of the radial artery does not adversely affect subsequent forearm function or blood flow to a clinically significant degree.
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Introduction
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Since its resurgence in the early 1990s the radial artery (RA) has been increasingly used in combination with bilateral internal mammary arteries to achieve total arterial myocardial revascularization [1]. There are few scientific data describing the short and long-term outcome of the forearm function and blood flow after RA removal and there are still concerns that its removal may effectively reduce forearm blood supply. There has been a recent report of a case of forearm ischemia after RA harvesting that highlights the need for research into this area, particularly as RA conduits are increasingly being used in younger patients undergoing CABG surgery [2, 3]. Thus most cardiac units at present still restrict harvesting of the RA to the nondominant arm and limit its use in patients with occupations involving fine finger dexterity. This study reports the effects of RA harvesting on early forearm circumference, neural sensation, handgrip power, exercise fatigue, and forearm blood flow (FBF) before and 3 months after CABG surgery.
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Patients and methods
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Patients
Twenty-three patients (aged 59.5 ± 1.2 years) with a negative modified Allen’s test (defined as reperfusion of the hand within 5 seconds of releasing the ulnar artery with occlusion of RA) undergoing CABG surgery using the RA as one of the conduits were recruited preoperatively. Risk factors for coronary artery disease were documented; 15.4% were diabetic, 57.5% hypertensive, 65.4% hypercholesterolemic, and 61.5% had a history of cigarette smoking. Ethical approval was obtained from the Royal Brompton and Harefield NHS Trust Ethics Committee and all patients gave written informed consent.
Patients underwent preoperative bilateral forearm function and FBF assessment on the day of admission. All patients completed the study, with a postoperative assessment at 3.4 ± 0.4 months. All vasoactive medications were stopped 24 hours before surgery.
Neural sensation
Objective neural sensation assessment was made with soft touch and pinprick sensations using cotton wool and pin, respectively [4].
Forearm circumference, handgrip power, and exercise fatigue
Forearm circumference was measured at the proximal third of the forearm between the antecubital crease and styloid process. Handgrip power was measured as the maximal voluntary contraction (MVC), assessed by patients gripping hard on a strain gauge, that provides a percentage of each grip. Sensitivity of the strain gauge was set and recorded for each patient as a reference for the postoperative assessment. Mean MVC was calculated after three measurements. Exercise fatigue was assessed with the patients cyclically gripping the strain gauge to a targeted visual force level (50% of MVC) for 6 seconds and then rested for 4 seconds [5]. Each patient repeated this 10-second cycle until they could no longer attain the targeted force level. The time in seconds was recorded as the duration of cyclical exercise fatigue.
Forearm blood flow
Forearm blood flow was measured by venous occlusion plethysmography, as previously described [6]. Briefly, patients rested supine in a quiet room at constant ambient temperature of 22oC for 15 to 30 minutes before FBF measurements were started. A blood pressure cuff was placed on the upper arm and inflated to 40 mm Hg with a rapid cuff inflator (D.E. Hokanson Model E-10; Bellevue, WA) to occlude venous outflow from the extremity. The resultant increase in forearm volume was measured with a mercury-filled silastic strain gauge placed around the proximal third of the forearm. The strain gauge was connected to a plethysmograph (D.E. Hokansen Model EC-4; Bellevue, WA) that was connected to a paper chart recorder (Multitrace 2; Lectromed, Jersey, Channel Islands) and the measurements were analyzed. Three resting base line FBF were measured. Patients then underwent forearm cyclical exercise until fatigue as described above, with a 2-minute period of ischemia immediately upon fatigue. Ischemia was induced by inflating the upper arm blood pressure cuff to a minimum of 40 mm Hg above systolic pressure. Blood flow (mL/100 mL/min) was measured immediately after cuff deflation and again at 1 and 5 minutes of reperfusion. Three measurements were obtained at each time period and the mean FBF was then calculated. Heart rate and systemic blood pressure were monitored for the study duration (Dinamap; Critikon, Tampa, FL).
Data analysis
All data were analyzed as within patient comparisons of preoperative with postoperative forearm function and FBF. Differences are presented as mean ± SEM and analyzed using paired Student’s t test. Data from the contralateral arm of each patient were used as individual controls. A p value less than 0.05 was considered significant.
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Results
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Neural sensation
There was no abnormality in objective soft touch sensation in either harvested or contralateral forearms. Three patients had minor objective reduction in pinprick sensation in the thenar eminence region of the harvested forearm, which did not affect daily use of the hand. All contralateral forearms had objective postoperative pinprick sensation that was unchanged.
Forearm circumference, handgrip power, and exercise fatigue
Forearm function measurements are shown in Table 1.
Contralateral forearms were significantly larger than the harvested forearms at both assessment periods (preoperative, p = 0.0004, and postoperative, p = 0.002). There was a significant reduction in postoperative forearm circumference in both forearms. (p < 0.05). Although no patients complained of any significant change in handgrip power the measured MVC in both the harvested and contralateral forearms was significantly reduced (p < 0.05). Postoperatively, exercise fatigue was improved in the contralateral forearm by 44% (p = 0.01) and by 20% in the harvested forearm (p = 0.25). There was no difference in mean MVC (preoperative, p = 0.10; postoperative, p = 0.11) and cyclical exercise fatigue (preoperative, p = 0.38; postoperative, p = 0.86) between the harvested and contralateral forearms.
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Table 1. Comparison of Preoperative and Postoperative Forearm Function Measurements in the Harvested and Contralateral Forearms
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Forearm blood flow
Changes in mean FBF at rest and after exercise-induced ischemia preoperatively and at postoperative assessments are shown in Figure 1.
Preoperative and postoperative FBF at rest, immediately after exercise ischemic reperfusion, and at 1 and 5 minutes of reperfusion were similar in both forearms. However, there was a positive trend toward higher postoperative FBF at each time period of reperfusion in the harvested forearm as compared with the contralateral forearm. There was no difference in FBF at rest or after exercise-induced ischemic reperfusion between the harvested and contralateral forearms at preoperative and postoperative assessments.
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Fig 1. Forearm blood flow responses at rest (0 minutes) and immediately after exercise-induced ischemic reperfusion, 1 and 5 minutes of reperfusion in (A) the harvested forearm (preoperative, diamonds; postoperative, squares) and (B) the contralateral forearm (preoperative, triangles; postoperative, circles). (FBF = forearm blood flow.)
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Comment
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Concern remains regarding the potential severe complications that may arise in the forearm from the harvesting the RA, particularly with the report of a patient developing an ischemic hand which required an interposition saphenous vein graft [3]. Despite the RA being used as an arterial conduit for the past decade, there are few data reporting the early and long-term changes in forearm function and FBF after RA harvesting. Most data available are observations from clinical series reporting a 5.4% postoperative complication rate with complications ranging from wound hematoma, infection, and scarring to localized nerve paraesthesia which in the majority of cases are transient in nature [7]. There were no wound infections in our cohort. Although 11% had objective paraesthesia in the thenar eminence related to injury to the lateral cutaneous antebrachial nerve, none of the 3 patients complained of significant clinical disabilities. Others have also reported similar neural effects [8].
The few available published data describing hand power and circulation changes are conflicting and do not correlate well with clinical observations [9, 10]. We observed a significant reduction in objective handgrip power of the harvested forearm. As similar degrees of reduction were also seen in the contralateral forearms, we concluded that this may be related to decreased use after surgery rather than to removal of the RA artery alone.
Further evidence supporting this was the small but significant reduction in forearm circumference observed in both forearms at the postoperative assessment. Significant reduction in thenar flexor power postoperatively has also been reported [9]. The clinical significance of these early findings is uncertain as none of the patients in our study complained of any subjective weakness in handgrip power. Cyclical exercise fatigue was not affected by the removal of RA and tended to improve at postoperative assessments. This may be due to the overall reduction in the mean MVC observed allowing the patients to perform longer cyclical handgrip exercise.
Our data indicate that removal of the RA does not reduce early postoperative FBF. This is not surprising as the blood flow to an organ, in this case the forearm, is not determined by the number of conduits present but by the cardiac output. We have also shown that the postoperative FBF tended to increase in the harvested forearm compared with the contralateral forearm, although this was not significant. The trend increased at 5 minutes of reperfusion compared with preoperative flow, indicating a prolonged duration of vasodilatation. This increase in flow has been shown to be the result of dilatation in the remaining vasculature [2, 11, 12]. The prolonged vasodilatation may be due to the delay in clearing of ischemic metabolites through collateral vessels in the harvested forearm.
Although the overall FBF or inflow to the hand does not appear to be reduced, other studies report a small but statistically significant decrease in digital blood flow after RA harvesting, particularly in the thumb and index finger [2, 13–15]. Others have shown a reduction in tissue perfusion of the hand and forearm but no change in hand function [16]. The clinical significance of this is uncertain as patients studied did not complain of any subjective disabilities. Ischemic claudication is also unlikely to occur, however the data are conflicting.
In conclusion, RA harvesting in patients with a negative modified Allen’s test does not adversely affect early forearm function or FBF responses.
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Acknowledgments
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William Chong was supported by the Kate Weeks Research Fellowship, Royal College of Surgeons, England, and the Clinical Research Committee Fellowship, Royal Brompton and Harefield NHS Trust.
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References
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Abstract
Introduction
