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Eur J Cardiothorac Surg 2005;27:1065-1069
© 2005 Elsevier Science NL

Skeletonized versus pedicled internal mammary artery: impact of surgical technique on post CABG surgery pain

Yaron Bar-Ela,b,*, Boaz Gilboaa, Nina Ungerb, Dorit Pudc,d, Elon Eisenberga,c,e

a The B. Rappaport Faculty of Medicine, Technion—Israel Institute of Technology, Haifa, Israel
b Department of Cardiac Surgery, Rambam Medical Center, Haifa 31096, Israel
c Haifa Pain Research Group, Haifa, Israel
d Haifa University, Haifa, Israel
e Pain Relief Unit, Rambam Medical Center, Haifa, Israel

Received 9 September 2004; received in revised form 14 February 2005; accepted 21 February 2005.

* Corresponding author. Address: Department of Cardiac Surgery, Rambam Medical Center, Haifa 31096, Israel. Tel.: +972 4 854 2631; fax: +972 4 854 2949. (E-mail: y_bar_el{at}rambam.health.gov.il).


   Abstract
Top
 Abstract
1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 References
 
Objective: Recent evidence suggests that coronary artery bypass graft (CABG) surgery often results in chronic chest wall pain, termed: ‘post CABG pain syndrome’ (PCP). Direct injury to intercostal nerves during the surgical procedure was presumed to underlie this syndrome. The aim of this study was to investigate the effect of two harvesting techniques of the internal mammary artery (IMA)—skeletonization (S-LIMA) and pedicle (P-LIMA) on the occurrence and incidence of PCP. Methods: A mailed questionnaire enquiring about the presence and characteristics of PCP was sent to all 482 patients who had undergone CABG in our institution in the years 1999–2000. A randomly chosen subgroup of IMA patients reporting PCP were summoned for evaluations of pain localization and intensity, thermal and tactile sensitivity, and disability assessment using recognized tests and indices. Results: Of the 380 responders (S-LIMA: 221, P-LIMA: 125, veins only V-34) 169 (44%) reported having PCP. Its prevalence was similar between the two IMA groups (S-LIMA: 45%, P-LIMA: 50%) but significantly lower in the V group (18%, P=0.003). Physical assessment in the subgroup of 43 IMA patients (S-LIMA: 22, P-LIMA: 21) performed 40.2±8.7 months after surgery confirmed equal occurrence of mostly left and midline chest wall neuropathic pain in both IMA groups. No significant differences were found between the two groups in respect to indices of pain intensity, thermal and tactile sensitivity and disability. Conclusions: PCP is a prevalent finding in post CABG patients. The skeletonization technique of IMA harvesting although causing significantly less inner chest wall trauma does not appear to reduce the occurrence of PCP. This finding may imply that ischemic injury rather than direct mechanical injury to the intercostal nerves is the putative mechanism underlying PCP.

Key Words: Coronary artery bypass graft • Surgery • Neuropathic pain • Internal mammary artery


   1. Introduction
Top
 Abstract
 1. Introduction
2. Materials and methods
 3. Results
 4. Discussion
 References
 
A recently recognized complication of CABG is the non-anginal chronic chest wall pain and disabling discomfort along and adjacent to the median sternotomy scar. Several recent studies have addressed this complication, termed post CABG pain (PCP), reporting incidences between 28 and 56% up to 2 years post-operatively [1–5]. The mechanisms underlying PCP are not entirely clear, yet PCP, neurogenic in character, is believed to be a consequence of nerve damage during dissection of the internal mammary arteries [1,6]. Since mobilizing the internal mammary artery as a skeletonized graft rather than a full thickness pedicle, tends to better preserve the integrity of the inner chest wall, preserve collateral sternal vascular bed and perfusion and decrease the rate of postoperative sternotomy related complications [7–10], we have postulated that the skeletonization technique of LIMA harvesting would also reduce the incidence of PCP.

This present study was undertaken to determine whether PCP incidence is lower in patients who had undergone CABG using the skeletonization technique for LIMA harvesting as compared to patients in whom the LIMA was harvested as a full thickness pedicle.


   2. Materials and methods
Top
 Abstract
 1. Introduction
 2. Materials and methods
3. Results
 4. Discussion
 References
 
2.1. Patients
The study was approved by the Rambam Medical Center Committee for Research on Human Subjects. All 482 patients who underwent primary CABG through median sternotomy between January 1, 1999 and December 31, 2000 at our institution form the cohort of this study. In 441 patients, (92%) the left internal mammary artery (LIMA) was harvested and used. The skeletonization technique was used in 281 (64%) of these patients (S-LIMA group) while pedicled LIMA was used in 160 patients (36%) (P-LIMA group). In the remaining 41 patients (8%) only saphenous veins were used (V group).

2.2. Surgical procedure
All IMA harvesting procedures were performed by three surgeons, using the same surgical technique. Following standard median sternotomy, the left hemisternum was elevated using Rultract® IMA Retractor (Rultract, Inc. Independence, OH, USA). The pleura was either left intact or opened longitudinally according to surgeon's discretion.

When the IMA was harvested as a pedicled conduit, a generous pedicle containing the IMA, accompanying veins, fat, fascia and lymphatics was mobilized using high voltage unipolar electrocautery. The pedicle was isolated from the epigastric bifurcation almost up to the IMA's origin. When the IMA was isolated in a skeletonized fashion, a longitudinal incision in the endothoracic fascia was performed at the limit between the artery and the medial accompanying vein; this incision was carried out with very low voltage unipolar electro-cautery to avoid any thermal damage to the arterial wall. Using the tip of the electro-cautery as a dissector, the branches of the IMA were exposed, clipped proximally and distally, and transected using Pott's scissors. Once branches were divided, scissors or low cautery were used to divide remaining medial and lateral soft tissue attachments. Dissection was carried out until the full length of the IMA was mobilized, from its most proximal part to its distal bifurcation usually at the sixth intercostal space.

Surgery was performed under mild hypothermia, using cardiopulmonary bypass and continuous retrograde blood cardioplegic arrest [11].

2.3. Study procedure
A mailed questionnaire with a self-addressed stamped return envelope was sent to all 482 patients. The questionnaire (in Hebrew, Arabic or Russian according to the patient's mother's tongue) included questions pertaining to the patients' current condition. Specifically, questions were focused on the presence of post surgery chest wall pain and discomfort. If such a pain was reported present, patients were asked to state whether it was different from their pre-surgery pain, to describe it, to grade its intensity and to describe its impact on their daily life activities. Chest pain or significant discomfort lasting more than 3 months and definitely different from the preoperative anginal chest pain and was defined as PCP. Attempts were made to contact by telephone all unresponsive patients.

Following the completion of this stage, a subgroup of randomly chosen PCP-positive patients were asked to undergo an extensive 3h long evaluation in the Pain Relief Unit of our institution.

The evaluation included the following (notably, all of the following are validated pain assessment tools):

(1) Exact localization of the painful site.
(2) Pain intensity as scored on a 10-cm blank visual analogue scale (VAS) [12].
(3) Assessment of exacerbating factors (such as walking, arm/shoulder movements, deep breathing, light touch, pressure application against the painful site and stress).
(4) Administration of the Short Form of McGill Pain Questionnaire (SFMPQ) [13]).
(5) The Pain Disability Index (PDI) [14].
(6) Application of three paintbrush strokes to the D2-D6 dermatomes on both sides of the chest wall and to a 3cm strip in width along the midline scar to determine the presence of hypoesthesia or mechanical allodynia (abnormal sensitivity to innocuous stimuli).
(7) Single pinpricks to assess mechanical hyperalgesia (worsening of response to painful stimuli).
(8) Thorough palpation of the chest wall for detection of local tenderness.
(9) Tuning fork for vibratory sensitivity testing.
(10) Quantitative thermal testing (QTT) [15] to determine the thresholds for warm and cold sensations and pain on both sides of the chest wall.

2.4. Statistical analysis
Statistical analysis was performed with the use of paired t-test or chi-square when appropriate. P<0.5 was considered significant. Data are presented as mean±standard deviation.


   3. Results
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
4. Discussion
 References
 
Three hundred and eighty patients, (79%) responded to the questionnaires (221/281, 79% in the S group, 125/160, 78% in the P group and 34/41, 84% in the V group). One hundred and two patients were lost to follow-up, 95 of them due to inability to contact because of either change of address or language difficulties. Seven patients have died after their discharge. The elapsed time from surgery to questionnaire filling was 30.5±7.1 months.

3.1. The preliminary questionnaire
Of the 380 respondents who form the basis for analysis, 169 (44%) reported having PCP according to our definition. PCP was reported by 100/221 (45%) of the responders in the S-LIMA group, by 63/125 (50%) in the P-LIMA group and by 6/34 (18%) in the V group (P=0.003). Other 38 patients (10%) (S-LIMA 20 (10%), P-LIMA 12 (10%) and V group 6 (18%)) reported having chest pain similar to the preoperative pain, and were, thus, regarded as having recurrent or residual anginal pain. The remaining 173 patients (46% of the responders) had no chest wall pain at all at the time they filled out the questionnaire. These findings are summarized in Table 1.


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  		Table 1. Summary of preliminary questionnaires
 
The demographic and pain characteristics of all patients with PCP are summarized in Table 2. No significant differences were found between groups in respect to age, gender, time from surgery or duration of pain. The chest pain was described by most patients to be at least moderate in severity (S-LIMA 69%, P-LIMA 60%, V-group 100%), and at least severely affected daily activities of 30% of all patients with PCP. One quarter of them were using analgesics regularly while only 6% had undergone an evaluation of their chest pain by a physician other than a cardiologist (i.e. pain specialist).


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  		Table 2. Demographic data and pain characteristics of the patients with PCP
 
3.2. Detailed physical evaluation
Randomly chosen 43 patients with PCP (S-LIMA 22, P-LIMA 21) underwent a thorough 3h-long personal interview and physical examinations by one of the authors (BG) in the hospital's Pain Relief Clinic. This subgroup's mailed questionnaire results were statistically similar to those of the remaining 120 patients, making them a reliable representative group. No significant differences were found between the S-LIMA and the P-LIMA subgroups in respect to age, gender, and time since surgery (Table 3).


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  		Table 3. Demographic data and pain characteristics of the subgroup of 43 patients with PCP who underwent personal interview and physical examination
 
3.3. Subjective pain characteristics
The intensity of pain, as measured by a verbal scale, ranged from mild to very severe. It was ranked as at least moderate by 20/22 (91%) of the S-LIMA group and by all 21 patients of the P-LIMA group. The mean pain intensity on the VAS of the entire sample was 47±20 with no significant difference between the two groups. Pain in both groups was mostly located and more intense on the left chest wall and along the scar while only two patients both in the S-LIMA group complained of mostly right-sided chest pain. No significant differences in pain intensity and characteristics were found between groups, and the most commonly used MPQ terms to describe the pain were in descending order tiring, aching, stabbing, sharp, tender, heavy and burning. The main aggravating factors included: coughing, light pressure on the scar and on the anterior chest wall, deep breathing, walking, cloth rubbing, weather changes and arms and shoulders movements. Pain was severe enough (≥5 on a 0–10 scale) to interfere with daily activities in 37(86%) patients. Working was most frequently affected, 25 patients; (14, S-LIMA, 11, P-LIMA), and sexual activity was reported to be limited by 17 patients (11 S-LIMA, 6 P-LIMA). The mean Pain Disability Index (PDI) for the entire group was moderate 4.5±3.4 (on a 0–10 scale). PDI scores were not found significantly different between S-LIMA and P-LIMA groups (P=0.91).

3.4. Objective findings
The physical examination revealed left chest sensory abnormalities (hypoesthesia, hyperalgesia or allodynia) in response to at least one type of mechanical stimuli (light touch, brush stroking, pinprick or vibration) in 19 subjects in each group, with a lesser prevalence on the right chest wall.

The QTT results showed no significant differences between the groups with respect to heat or cold sensation and pain thresholds. No differences were found between the left and right sides of the chest in both groups. Mechanical sensations and pain thresholds were equal in both groups.


   4. Discussion
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
References
 
In consistency with previously reported 28–56% prevalence of PCP [1–4], the results of the present study indicate that chronic anterior chest wall pain is common among patients who had undergone CABG surgery.

One potential shortcoming of our study results from the fact that not all mailed questionnaires were answered. Although a 79% response rate is a common finding in studies of similar design, we cannot rule out the possibility that the non-responders are patients who did not have pain. It that case, the overall prevalence of PCP would have been only 35%. However, since the response rate of all three sub-groups was similar (78–84%) we suspect that the relative prevalence of PCP between the groups would have been the same, had all patients responded

The results also indicate that the surgical technique of harvesting the IMA, whether skeletonized or pedicled has no effect on the prevalence and characteristics of PCP. Interestingly, the control group, in whom only the saphenous vein was used for grafting while the IMA was left untouched, was found to have a significantly lower prevalence of PCP.

These results contradict those of a preliminary report by Aebert et al., (Aebert H, Froehlich V, Menon A, Melms A, Ziemer G. Skeletonizing technique of the internal thoracic artery reduces intercostal nerve damage. 2nd EACT/ESTS Joint meeting, Vienna Austria 12–15/10/2003 Unpublished data), who conducted a prospective study in which they compared the prevalence of PCP following these two harvesting techniques. The authors reported that chest wall pain and tenderness was present 7 months after surgery in 45% (9/20) of the pedicled group versus only 5% (1/20) in the skeletonized group, and concluded that the skeletonized technique is significantly superior compared to the pedicled technique in terms of reducing nerve damage and PCP prevalence. The differences in the results between the two studies are large and difficult to explain. Yet, one should wonder about the extremely low prevalence (5%) of PCP in the skeletonized group reported by Aebert et al. since the prevalence of PCP in the control group of our study, in whom the IMA was not harvested at all, was 18%. Furthermore, in another study [3], in which only sternotomy and thymectomy were performed without any harvesting of the internal mammary arteries, chronic chest pain and discomfort were reported by 27% of the patients. It seems, therefore, unlikely that sternotomy of any kind will result in only 5% prevalence of chronic chest wall pain.

Another question raised from the results of the present study is related to the mechanisms underlying PCP. The abnormal findings in the sensory examination of the chest wall in the present study as well as in previous reports of PCP [1,6] clearly indicate that intercostal nerves are injured during the surgical procedure, and therefore suggest that the majority of patients with PCP suffer neuropathic pain or, in other words, post-traumatic neuralgia.

The question then is what causes the intercostal nerve injury during CABG surgery? One possible mechanism is a direct injury to the nerves during the harvesting procedure. The pedicled technique consists of mobilization of the IMA using high grade electrocautery within a tissue pedicle that includes beside the artery, the internal mammary vein, endothoracic fascia and fat whereas in the skeletonized technique the artery is mobilized with only minimal injury to the surrounding tissues. Our assumption was that if direct nerve injury is the underlying mechanism of PCP, then a lower prevalence of PCP would be expected when the IMA is mobilized skeletonized. This, however, was not found in the present study. Other possible mechanisms are tension or compression of the intercostal nerves during chest wall retraction. The possibility of this mechanism of injury is supported by the fact that PCP is reported not only subsequent to CABG surgery, but also following sternotomy and thymectomy [3]. The results of the present study, however, indicate that when the IMA is removed, regardless of the harvesting technique, the prevalence of PCP is higher compared to its prevalence in patients in whom only veins were used as conduits. A third possible mechanism—ischemic intercostal neuropathy may explain these findings. Despite studies that have shown reduced sternal ischemia following skeletonized IMA harvesting [8,16,17], the arterial blood supply to the nerves may be equally affected by both techniques. Yet it is still possible that even the minimal tissue damage inflicted by the low voltage electro-cautery during the skeletonization process is sufficient to inflict damage to the adjacent intercostal nerves resulting in PCP.

In summary, this study highlights once more the high prevalence of PCP among patients who had undergone CABG and its detrimental effects on their well-being and life style. Our findings suggest that PCP may have a neuropathic component, and is likely to involve mechanical tension or compression as well as ischemic injuries to the intercostal nerves. According to the present study the harvesting technique of the IMA, does not alter the prevalence of PCP. Large scale prospective studies using different surgical techniques, or alternatively, various methods of perioperative analgesia and neuroprotection aimed at reducing the prevalence of PCP are required.


   Footnotes
 
{star} Presented at the joint 18th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 12th Annual Meeting of the European Society of Thoracic Surgeons, Leipzig, Germany, September 12–15, 2004.


   References
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 References
 

  1. Eisenberg E, Pultorak Y, Pud D, Bar-El Y. Prevalence and characteristics of post coronary artery bypass graft surgery pain (PCP). Pain 2001;92:11-17.[Medline]
  2. Meyerson J, Thelin S, Gordh T, Karlsten R. The incidence of chronic post-sternotomy pain after cardiac surgery—a prospective study. Acta Anaesthesiol Scand 2001;45:940-944.[Medline]
  3. Kalso E, Mennander S, Tasmuth T, Nilsson E. Chronic post-sternotomy pain. Acta Anaesthesiol Scand 2001;45:935-939.[CrossRef][Medline]
  4. Bruce J, Drury N, Poobalan AS, Jeffry RR, Smith WCS, Chambers WA. The prevalence of chronic chest and leg pain following cardiac surgery: a historical cohort study. Pain 2003;104:265-273.[CrossRef][Medline]
  5. Rowe MA, King KB. Long-term chest wall discomfort in women after coronary artery bypass grafting. Heart Lung 1998;27(3):184-188.[Medline]
  6. Mailis A, Umana M, Feindel CM. Anterior intercostal nerve damage after coronary artery bypass graft surgery with use of internal thoracic artery graft. Ann Thorac Surg 2000;69(5):1455-1458.[Abstract/Free Full Text]
  7. Cunningham JM, Gharavi MA, Fardin R, Meek RA. Considerations in the skeletonization technique of internal thoracic artery dissection. Ann Thorac Surg 1992;54:947-950.[Abstract]
  8. Parish MA, Asai T, Grossi EA, Esposito R, Galloway AC, Colvin SB, Spencer FC. The effects of different techniques of internal mammary artery harvesting on sternal blood flow. J Thorac Cardiovasc Surg 1992;104(5):1303-1307.[Abstract]
  9. Matsa M, Paz Y, Gurevitch J, Shapira I, Kramer A, Pevny D, Mohr R. Bilateral skeletonized internal thoracic artery grafts in patients with diabetes mellitus. J Thorac Cardiovasc Surg 2001;121:668-674.[Abstract/Free Full Text]
  10. Athanasiou T, Crossman MC, Asimakopoulos G, Cherian A, Weerasinghe A, Glenville B, Casula R. Should the internal thoracic artery be skeletonized?. Ann Thorac Surg 2004;77(6):2238-2246.[Abstract/Free Full Text]
  11. Bar-El Y, Adler Z, Kophit A, Kertzman V, Sawaed S, Ross A, Cohen O, Milo S. Myocardial protection in operations requiring more than 2h of aortic cross-clamping. Eur J Cardiothorac Surg 1999;15(3):271-275.[Abstract/Free Full Text]
  12. Price DD, McGarth PA, Rafii A, Buckingham B. The validation of visual analogue scale as a ratio scale measures for chronic and experimental pain. Pain 1983;17:45-56.[CrossRef][Medline]
  13. Melzack R. The McGill Pain Questionnaire: major properties and scoring methods. Pain 1975;1(3):277-299.[CrossRef][Medline]
  14. Pollard CA. Preliminary validity study of the pain disability index. Perceptual Motor Skills 1984;59:974.
  15. Yarnitsky D, Fowler C. Quantitative thermal testing. In: Osselton JW, editor. Clinical neurophysiology. Oxford: Butterworth-Heinemann; 1995. pp. 253-270.
  16. Lorberboym M, Medalion B, Bder O, Lockman J, Cohen N, Schachner A, Cohen AJ. 99mTc-MDP bone SPECT for the evaluation of sternal ischaemia following internal mammary artery dissection. Nucl Med Commun 2002;23(1):47-52.[Medline]
  17. Cohen AJ, Lockman J, Lorberboym M, Bder O, Cohen N, Medalion B, Schachner A. Assessment of sternal vascularity with single photon emission computed tomography after harvesting of the internal thoracic artery. J Thorac Cardiovasc Surg 1999;118(3):496-502.[Abstract/Free Full Text]



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