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Interact CardioVasc Thorac Surg 2007;6:598-602. doi:10.1510/icvts.2007.151795 © 2007 European Association of Cardio-Thoracic Surgery
Arm temperature distribution in thermographic pictures after radial artery harvesting for coronary bypass operation ukasz Jaworski*Department of Cardiosurgery, Medical University of Gdansk, ul. Debinki 7, 80-211 Gdansk, Poland Received 8 January 2007; received in revised form 23 May 2007; accepted 23 May 2007
*Corresponding author. Tel.: +48 58 3492403; fax: +48 58 3417669.
The radial artery (RA) beside the left internal mammary artery and veins is often used for coronary artery bypass grafting. The aim of this study was to assess arm temperature changes after removal of the radial artery and determine whether there is an effect on hand function. Between April and December 2005, fifty patients underwent myocardial revascularization employing the pedicle RA as one of the coronary grafts. The study protocol included thermographic and clinical examination one day before the surgery and on the sixth day after the procedure. An Agema 900 Thermovision System was used for thermographic evaluation. Thermovision examinations were carried out at rest and after a handgrip test before and after radial artery harvesting. Temperature was measured on each finger and on the forearm (separately on the radial and ulnar side of the forearm). All examinations were performed in the same conditions. Hand endurance was compared with the 2 min handgrip test before and after the surgery. A comparison of hand temperature changes during the handgrip test before and after radial artery harvesting showed no significant difference (P>0.05). Before the surgery a significant increase in temperature over the ulnar artery was observed after the handgrip test. There were no clinical symptoms of acute or subacute hand ischemia. No clinical evidence of hand claudication was detected. There was no significant difference in hand endurance after radial artery harvesting. This study suggests that removal of the radial artery changes the hand temperature distribution but does not affect hand function in the short-term. In the study group, radial artery harvesting did not cause clinically relevant changes in blood support of the arm.
Key Words: Radial artery; Hand function; Handgrip test; Temperature distribution
Carpentier first attempted use of the radial artery in coronary artery bypass surgery in the early 1970s [1]. After a few years, usage of the radial artery was abandoned due to the poor early angiographic patency rate. In 1992, after Acar and co-workers, dispatched idea of radial artery use was restored [2]. Since then the radial artery has been widely used in coronary bypass grafting. Subsequently, angiographic patency of the radial artery has been found to be good [3, 4]. There has been an understandable concern that radial artery harvesting might affect the perfusion and function of the hand and forearm. Many studies proved that radial artery (RA) harvesting is safe and free from complications [5, 6]. In this prospective study, hand and forearm perfusion was determined by measuring temperature changes of a donor hand before and after radial harvesting. Temperature was measured at rest and after handgrip test by means of an Agema 900 Thermovision System. The aim of the study was to assess the effect of radial artery harvesting on hand function and correlation of hand temperature changes with postoperative arm function.
The study group consisted of fifty patients undergoing coronary artery bypass grafting with radial artery harvesting at the Department of Cardiosurgery between April and December 2005. The radial artery was harvested from the left arm (non-dominant) in every patient. A decision concerning surgical technique (for example number and sort of grafts) was made by a surgeon on the basis of coronary artery angiography and clinical data. Patients older that 77 years, with unstable angina, renal insufficiency or peripheral atherosclerosis were excluded from the study. The adequacy of collateral ulnar blood flow was assessed preoperatively with Allen's test and subsequently in the operating room with modified Allen's test using a pulsoxymeter. Radial artery harvesting was performed in the standarized manner using a combination of diathermy and sharp dissection. Thermographic examination was performed with an Agema Thermovision System 900SW/TE. This is a non-invasive, very sensitive method working in infrared spectrum. Thermographic pictures were presented in a 256 iron color scale. In order to increase measurement sensitivity thermograms were analyzed in an eight-color medical scale. Thermograms were analyzed using an IRwin Research v.2.01 software. An example of a thermographic picture before surgery at rest (Fig. 1) and after radial artery harvest (Fig. 2).
Thermographic examination was performed in the operating room in order to provide constant environment conditions (air temperature, humidity) one day before and six days after the procedure. The study protocol assumed thermographic examination both at rest and after a 2 min handgrip test. Temperature changes at the following measurement points were analyzed statistically:
Temperature difference (delta) between resting condition and after the handgrip test was calculated for pre- and postoperative temperature values of every measurement point according to the formula:
Hand function was evaluated by neurological examination after radial artery harvesting. Strength of the hand was measured using a hand-held dynamometer before and after the procedure. The results were analyzed with Statistica v. 6.0.
No ischemic complication of the hand or forearm was observed after radial artery harvesting. 3.1. Influence of handgrip test on arm temperature before and after radial artery harvesting Before radial artery harvesting the temperature of the fingers (T1–T5) decreased statistically significantly after the hand grip test. In contrast, the temperature over the ulnar artery (ARO1) increased after exertion. However, the temperature difference before and after the hand grip test in the region of the radial artery (ARO2) did not reach statistical significance (Fig. 3a).
After radial artery harvesting the temperature of the fingers (T1–T5) decreased statistically significantly after the hand grip test. In contrast to the behavior before radial artery harvesting, after radial artery removal the temperature over the ulnar artery (ARO1) did not change after exertion and the temperature over the radial artery (ARO2) decreased after the handgrip test. 3.2. Influence of radial artery harvesting on resting temperature of the arm The temperature of the arm decreased significantly over the harvested radial artery (ARO2), over the ulnar artery (ARO1) and on the thumb (T1) after the surgical procedure. The temperature differences in the remaining fingers (T2–T5) were lower after radial artery harvesting, but these changes did not reach statistical significance (Fig. 3b).3.3. Influence of radial artery harvesting on arm temperature after handgrip test The skin temperature after the handgrip test decreased significantly in the region of the ulnar and radial artery (ARO1 and ARO2) and also on the thumb (T1) after radial artery harvesting. Temperature differences of the remaining points (T2–T5) were not statistically significant (Fig. 4a).
3.4. Arm temperature delta on handgrip test before and after radial artery harvesting The aim of this analysis was to show differences in arm temperature changes after the handgrip test in two conditions: before and after radial artery harvesting. The only significant difference was observed for temperature of the ulnar area (dARO1). An increase in temperature after the handgrip test before radial artery harvesting resulted in negative values of dARO1. An opposite trend was observed for temperature behavior after radial artery harvesting (positive dARO1). No statistically significant difference was observed between hand and radial area temperature delta (dT1k–dT5k and dARO2) for the handgrip test before and after radial artery harvesting (Fig. 4b). Mean values of full dynamometer closure were 91.9±19.3 before surgery and 92.6±20.5 after the procedure. None of the patients reported significant deterioration in performing daily activities or other usual tasks.
Before radial artery harvesting, the temperature of the fingers decreased after the handgrip test. The highest decrease in temperature was observed on the 2nd finger with the maximum of 0.9 °C. After radial artery harvesting, similar changes of finger temperatures were noted after exertion, however, resting temperature was lower than the temperature before the surgery. This statistically significant decrease in finger-tip temperature after exertion can result from physiological reaction on squeezing maneuver with the hand dynamometer. This reaction is caused by limitation of finger perfusion during shortening of the lumbrical muscles. Before radial artery harvesting, a significant increase in the temperature was observed in the area over the ulnar artery on exertion, due to the heat released from the muscles of the forearm and increase of blood flow through the ulnar artery. This is the physiological response to exertion of the hand. After radial artery harvesting a decrease in temperature was observed in the region of the radial artery due to closure of the vessels leading to the subcutaneous tissue and skin. In order to provide proper perfusion by the ulnar artery, flow through this vessel and its dimension increase [7]. Hence, in spite of increased flow through the ulnar artery after radial surgery, finger temperature before and after radial artery harvesting did not differ significantly neither at rest nor on exertion. This results from the physiological reaction of flow restriction through the ulnar artery branches leading to the subcutaneous tissue and skin. Resting temperature of the first finger decreased significantly after radial artery harvesting from 31.9±2.1 °C to 30.4±2.3 °C (difference of 1.5 °C). Temperature differences of the other finger did not reach statistical significance. A decrease in skin temperature of the forearm was observed both over the radial and ulnar artery at rest and after the surgery (average of 0.6 °C). Patterns of temperature changes before and after radial artery harvesting assessed with a 2 min handgrip test were similar. After radial artery harvesting, temperature on exertion decreased significantly only on the first finger (average of 1.2 °C). It is worth mentioning that after radial surgery exertion the temperature on the other fingers decreased without statistical significance. But forearm temperature on exertion the over the ulnar artery decreased significantly after radial artery harvesting. In terms of maintaining good function of the upper extremity after radial artery harvesting, changes of exertion temperature after surgery seem to be the most relevant. A big decrease in temperature on exertion can indicate an insufficient perfusion and hand ischemia. In our study, changes of finger temperature on exertion before and after radial artery harvesting did not differ significantly. The only significant change of skin temperature was observed on the forearm over the ulnar artery. After radial artery harvesting an increase in temperature on exertion is lower than before the surgery. It can be explained by change of distribution in hand perfusion [8]. Flow and dimension of the ulnar artery increased after radial artery harvesting. The thermovision system measures the surface temperature. Restriction of the flow through the subcutaneous branches of the ulnar artery results in cooling the region of the skin over the ulnar artery after radial artery harvesting, which is a physiological phenomenon. In our cohort, function of the arm was not impaired in any patient after radial artery harvesting. We did not observe any signs of insufficiency of hand perfusion neither in the early postoperative period nor during the follow-up. Acar et al. are the ones who favor the Allen's test the most. They report 3.9% of Allen's test results being false negative [2]. Doppler ultrasonography was performed if results of the Allen's test were not clear. There was no contraindication for radial artery harvesting in any patient. The conclusion drawn by Acar that radial artery harvesting is not harmful, and that the Allen's test is clinically reliable and sufficient for preoperative assessment, were confirmed by other authors. Brodman et al. showed an increase in blood flow and dimension of the ulnar artery after radial artery harvesting eight weeks after the surgery by photoelectric pletysmography and Doppler ultrasonography [7]. Moreover, they showed some decrease in hand perfusion but without clinical relevance and function impairment [7]. Royse et al. also claim that radial artery harvesting does not result in limitation of hand perfusion [8]. They showed that closure of the radial artery by external pressure in the region of the wrist results in flow increase through the ulnar artery. Pola et al. also confirmed an increase in blood flow through the ulnar artery 10 days and one year after radial artery harvesting [6]. Hyun-Sung and Byung-Chal showed a decrease in finger perfusion, however, the tendency of blood flow increase in the first two fingers could be recognized [9]. The impairment of hand perfusion did not lead to clinically relevant symptoms. They also showed the results of long follow-up after radial artery harvesting with the assessment of hand and forearm perfusion by volume pletysmography [10–12]. In contrast to a decrease in finger perfusion in an early postoperative period, blood flow returns to values before radial artery harvesting three years after surgery [13]. In a long postoperative period physiological reactions make the palmar arteries provide finger perfusion on a preoperative level only through the ulnar artery. Dumanian et al. showed that harvesting of the radial artery has no influence on the functional status of the hand [5]. The only symptom influencing hand function was thumb tingling. Meharwal and Trehan showed good results after radial artery harvesting in a group of 3977 patients, which encourages the routine use of the radial artery [14]. Radial artery harvesting has no influence on muscle strength of the hand and forearm [5, 7, 14]. In our cohort, the Allen's test was sufficient to confirm patency of the collaterals before radial artery harvesting. There was no contraindication for radial artery harvesting in any patient. There was no symptom of upper extremity ischemia after the surgery in any patient. Temperature changes after radial artery harvesting had no clear influence on postoperative function of the hand, which was preserved in every patient. A long-term follow-up with thermovision examination is needed in patients after radial artery harvesting in order to assess changes in hand and forearm perfusion.
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Abstract
1. Introduction
