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Eur J Cardiothorac Surg 2005;28:420-424
© 2005 Elsevier Science NL
Original articles |
a Department of Cardiovascular Surgery, Osmangazi University, Medicine Faculty, Visnelik Mh. Karatay Sk., No: 3/31 B-Blok, 26020 Eskisehir, Turkey
b Department of Neurology, Osmangazi University, Medicine Faculty, Eskisehir, Turkey
Received 25 April 2005; received in revised form 1 June 2005; accepted 2 June 2005.
* Corresponding author. Tel.: +90 222 2397828; fax: +90 222 2251659. (Email: mikizler{at}ogu.edu.tr).
Abstract
Objective: Radial artery (RA) is now used widely as a conduit of choice in coronary artery bypass grafting. Although RA removal is considered safe in the presence of adequate collateral arterial supply, there is still a considerable suspicion on the functional status of the forearm and hand. However, a neurological dysfunction may occur owing to either surgical trauma or ischemic neuropathy. This study was aimed to investigate the functional outcome of the donor forearm nerves of the patients who underwent coronary artery bypass grafting surgery with RA conduits. Methods: A consecutive series of 50 patients who underwent coronary artery bypass graft surgery with one or two RA grafts were investigated in the study. Motor and sensory functions of donor forearm nerves were measured by ENMG studies, pre- and postoperatively at the third week and sixth month of the operation. The conduction velocities, distal latencies and amplitudes of action potentials for motor and sensorial conductions of radial, ulnar and median nerves were measured in each ENMG examination. Neurologic status of the donor forearm and hand was assessed by the same neurologist who performed a detailed neurologic physical examination and ENMG studies. Results were statistically compared using one-way ANOVA test. Results: The incidence of any neurologic symptoms was 32% in early postoperative period. All reported neurologic complaints were associated with sensory conduction deceleration in ENMG investigations of related nerves. In postoperative assessment, median nerve sensory-motor, and ulnar nerve motor conduction records were slightly lower than the preoperative values, but no statistical difference was observed. Pre- and postoperative radial nerve motor and sensory conduction records were statistically similar (P>0.05). Conclusions: We advocate that removal of RA does not lead to any major neurologic hand complications in the presence of adequate collateral arterial blood supply. ENMG studies confirmed minimal conduction alterations with no statistical significance, even if neurologic symptoms were stated.
Key Words: Radial artery • Graft • Coronary revascularization • Neurological injury • Neurologic complication • Coronary artery bypass grafting • Forearm • Hand • Complication
1. Introduction
Radial artery (RA) has been increasingly used as a conduit of choice in coronary artery bypass grafts. Simpler technique of harvesting and good patency outcomes provided a more common use for RA grafts [1,2]. Although RA removal is safe depending on adequate collateral arterial supply, some surgeons are still concerned about it because of ischemia and poor neurologic outcome risks at donor forearm and hand. In the literature, few complications of RA harvesting such as severe ischemia of hand [3] and infections at harvesting site [4] are reported. Nevertheless, neurologic complications of RA harvesting are reported as a rare surgical complication resulting from direct radial nerve damage during surgery [5,6]. Denton and colleagues [7] also pointed out that median and radial nerve injuries may be a consequence of hypoperfusion of hand following to RA removal as well as direct surgical trauma to radial, median and ulnar nerves and their branches supply the motor and sensorial functions in the forearm. Potential responsible mechanisms for the neurologic complications at hand following RA removal are inadequacy of the blood flow at the hand and its adverse effects on the nerve conduction network. In the aim to investigate sensory and motor complications of the forearm nerves, we prospectively performed pre- and postoperative nerve conduction studies in donor forearms of the patients who underwent coronary artery bypass grafting surgery with RA conduits.
2. Materials and methods
2.1 Patients
This study was approved by The Osmangazi University Institutional local ethics committee on human research. From August 2002 to August 2003 a consecutive series of 50 patients (34 men, 16 women) (mean age±SD; 59±5 years) who underwent coronary artery bypass graft surgery using 54 radial artery grafts were investigated in the study. Table 1
shows the characteristics of patients. Thirteen patients (26%) were diabetic, and nine (18%) had metabolic syndrome characteristics [8]. Patients with past forearm injury or rheumatic diseases were excluded for RA harvesting. Patients who had suspicious neurologic complaints in forearm, indicating peripheral neuropathy such as carpal tunnel syndrome were also excluded. Evaluation of adequate ulnar artery supply was initially checked by Allen's test [9] and patients with capillary refilling within 10s were considered as a candidate for RA harvesting. In these patients, arterial blood supply at hand was also examined in operating theater by digital pulse oxymetry (Datex-Ohmeda Division Instrumentarium Corp, Helsinky, Finland) with its probe at the thumb. Modified Allen's test was repeated in this position, and RA removal was considered safe either the pulse wave of the thumbnail bed reappeared within 10s or systemic SPO2 value was achieved with the radial artery compressed at wrist.
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2.3 Data collection
Nerve conduction velocities were measured by ENMG studies, pre- and postoperatively at the third week and sixth month of the operation. Neurologic status of the donor forearm and hand was assessed by the same neurologist who performed a detailed neurologic physical examination and ENMG studies.
Neurologic examination included assessing the finger strength and sensation to define abnormalities such as tingling, numbness or pain in either dorsal or palmar surface of the hand. Nerve conduction studies were performed using Saphire 4ME (Medelec, Surrey, England). Compound muscle action potential amplitudes, distal latencies, conduction velocities and amplitudes for both motor and sensory stimulations were calculated separately. The stimulation and recording points during ENMG for each forearm nerves are shown in Fig. 1 .
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2.4 Statistical analysis
Results were expressed as means±SEM. Statistical analysis was performed using ANOVA (variance analysis for multiple comparisons). The post hoc Tukey multiple range test was used after ANOVA and P<0.05 considered as statistically significant.
3. Results
All surgeries were successful and no major complications ensued. None of the patients had hematoma requiring drainage. Improvement of subjective symptoms and physical findings followed an uneventful course.
3.1 Hand function
We did not notice any serious hand complications in our patients such as severe hand ischemia. The incidence of any neurologic symptoms was 32% in early postoperative period. Sensation abnormalities were described in 28% of patients and most commonly reported complaints were paresthesia and numbness. Paresthesia on the ulnar nerve region of hand occurred in 12% of patients, and on the median nerve region in 16%. Thumb weakness was seen in 6%. After 6 months of follow-up, neurologic complications remained as numbness only in two patients (4%), and others reported that their symptoms improved in 3–6 months. Evaluation of 16 patients with any neurologic symptoms revealed that, 11 patients (68.75%) were diabetic, and 7 (43.75%) patients had metabolic syndrome characteristics. The rates of neurologic abnormalities are presented in Table 2
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The mean values and standard deviations of distal latencies, amplitudes, velocities of motor and sensory conductions in the preoperative, the first month and the sixth month of operation are shown in Table 3 .
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After re-suggested by Acar and colleagues [10] with modified harvesting technique and use of pharmacological dilatation agents, RA is now used widely as a conduit of choice in coronary artery bypass grafts. Despite removal of radial artery is considered safe in the presence of adequate blood supply of ulnar artery, there is still a considerable suspicion on the functional status of the forearm and hand because of the risk of decreased tissue perfusion. In this regard, the effects of radial artery harvesting on tissue perfusion and function of the hand have been studied by many investigators [11,12]. Denton and colleagues [7] have pointed out the neurological dysfunction, occurred owing to either surgical trauma or ischemic neuropathy, as the underlying potential mechanism of functional hand complications after RA harvest. They performed a written interview with patients who underwent coronary artery bypass surgery with a RA conduit, to reveal symptoms related to nerve damage. This elaborated report prompted us to perform a detailed physical examination and investigate nerve conduction abnormalities using ENMG studies in donor arms of the RA harvested patients.
In a recent study, where a similar harvesting technique was performed, hand complications due to RA harvesting was reported as 9.0% in both cold and harmonic scalpel use [12]. In the present study, any neurologic symptoms were reported 32%. Although taking a special care, either surgical incision or thermal damage of electrocautery can be responsible for the direct nerve injury during RA harvesting. These effects may be attributed to sensory symptoms because of anatomic proximity of the superficial radial and antebrachial cutaneous nerves to the harvesting site. But, it is difficult to explain thumb weakness with these reasons, because median nerve lies far from RA, where it could not be affected easily from surgical manipulations. Sadaba and colleagues [13] suggested that removal of RA reduces the tissue perfusion of the hand and forearm. Median nerve receives blood supply from both radial and ulnar arteries. In this respect, thumb weakness is deemed as a result of temporary median nerve ischemia after removal of RA in early postoperative period even if preoperative tests indicated adequate collateral blood supply. One possible explanation to this phenomenon is the dominance of the artery, which provides most of collaterals to the median nerve. Dominance of radial artery determines the patients who are exposed to median nerve neuropathy after operation.
In the present study, both median and ulnar nerves sensory and motor conduction records were slightly lower compared to preoperative values, especially in the patients with neurologic complaints. Despite no statistical difference was observed, it is clear that, neurologic complications of the hand after RA harvest is consistent with a modest deceleration in neurologic conduction of the related nerves. The incidence of diabetes in the patients with any neurologic complaints was 68.75%. Metabolic syndrome was also found in a high rate in these patients. In this regard, it is possible to speculate that diabetes mellitus and metabolic syndrome are predisposing factors to neurologic complications in the RA harvested patients. According to presented results, only a modest deceleration can be achieved on conduction velocities of forearm nerves after radial artery harvest, even in diabetics. However, statistical analysis did not show any significant difference between the preoperative and postoperative records.
In summary, RA grafts, sometimes even bilaterally, are used in large series, in the aim of achieving total arterial revascularization [14]. Despite acceptable minor hand complications are reported in many studies [15,16]; none of them could eliminate controversy about the suspicions on this conduit. The current study highlights that removal of RA does not lead to any major neurologic hand complications in the presence of adequate collateral arterial blood supply. ENMG studies confirmed minimal conduction alterations with no statistical significance, even if neurologic symptoms were stated. We advocate RA as a safe conduit of choice in coronary artery bypass grafts to increase the number of arterial anastomoses. In order to avoid serious hand complications due to RA removal, Allen's test should be performed carefully in all patients before surgery.
References
This article has been cited by other articles:
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  S. Bleiziffer, I. Hettich, B. Eisenhauer, D. Ruzicka, B. Voss, R. Bauernschmitt, and R. Lange Neurologic sequelae of the donor arm after endoscopic versus conventional radial artery harvesting J. Thorac. Cardiovasc. Surg., September 1, 2008; 136(3): 681 - 687. [Abstract] [Full Text] [PDF]
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 S. Nishida, Y. Kikuchi, G. Watanabe, M. Takata, S. Ito, and K. Kawachi Endoscopic Radial Artery Harvesting: Patient Satisfaction and Complications Asian Cardiovasc Thorac Ann, February 1, 2008; 16(1): 43 - 46. [Abstract] [Full Text] [PDF]
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 G. Reyes, A. Traba, L. Lopez, A. Pinto, J. Duarte, and J. L. Vallejo Neurological damage after radial artery harvesting in coronary surgery: a direct measure Interactive CardioVascular and Thoracic Surgery, August 1, 2006; 5(4): 433 - 438. [Abstract] [Full Text] [PDF]
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