Among the potential advantages of minimally invasive

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1 Endoscopic Internal Thoracic Artery Dissection Leads to Significant Reduction of Pain After Minimally Invasive Direct Coronary Artery Bypass Graft Surgery Jan Bucerius, MD, Sebastian Metz, MD, Thomas Walther, MD, PhD, Volkmar Falk, MD, PhD, Nicolas Doll, MD, Frank Noack, MD, David Holzhey, MD, Anno Diegeler, MD, PhD, and Friedrich W. Mohr, MD, PhD Department of Cardiac Surgery, Heartcenter, University of Leipzig, Leipzig, Germany Background. The aim of this study was to evaluate postoperative pain levels after endoscopic versus conventional internal thoracic artery (ITA) dissection for minimally invasive direct coronary artery bypass graft surgery (MIDCABG) surgery. Results were compared with pain levels associated with conventional cardiac bypass operations through a median sternotomy. Methods. Of 190 patients included in this prospective study, 24 patients had endoscopic ITA takedown (MID- CABG-endo) using the da Vinci telemanipulator followed by a manual coronary anastomosis through a left minithoracotomy. A conventional MIDCABG operation (MIDCABG-conv) was performed in 73 patients with ITA preparation under direct vision. Postoperative pain levels after conventional CABG through a median sternotomy (CABG-conv, n 93) served as controls. A standarized questionnaire including visual analog scale (VAS) was used for prospective pain assessment from POD1to7. Results. Pain levels (VAS) declined in all groups from POD 1 to 7. Overall pain levels were significantly lower in the MIDCABG-endo group as compared with MID- CABG-conv and CABG-conv groups, respectively (p < 0.001, general linear model). There was no significant difference between the MIDCABG-conv and CABG-conv (p not significant, general linear model) groups. Furthermore, patients after MIDCABG-endo required fewer nonsteroidal anti-inflammatory drugs and opioid medications, postoperatively. Conclusions. An endoscopic ITA takedown in MID- CABG surgery leads to significantly reduced postoperative pain levels possibly because of less rib retraction. (Ann Thorac Surg 2002;73:1180 4) 2002 by The Society of Thoracic Surgeons Among the potential advantages of minimally invasive direct coronary artery bypass graft (MID- CABG) surgery are reduction of trauma, better cosmetic results, and faster recovery. Significantly higher pain levels have been reported for MIDCABG on the first 2 postoperative days when compared with standard CABG procedures [1 3]. Intercostal application of local anesthetic agents or intraoperative cryoablation of the fifth intercostal nerve have been subsequently introduced [3]. In order to further minimize surgical access computerenhanced endoscopic techniques have been introduced. Using the da Vinci telemanipulation system (Intuitive Surgical, Mountain View, CA) total endoscopic bypass grafting has been achieved [4, 5]. By avoiding the rib retraction necessary for internal thoracic artery (ITA) dissection under direct vision, this technique may help to reduce postoperative pain. The aim of this study was to prospectively evaluate Accepted for publication Nov 15, Address reprint requests to Dr Bucerius, Department of Cardiac Surgery, Heartcenter, University of Leipzig, Strümpellstrasse 39, Leipzig, Germany; bucerj@medizin.uni-leipzig.de. postoperative pain levels after endoscopic computer enhanced versus conventional ITA takedown in MIDCABG surgery. Pain levels after conventional CABG through a median sternotomy served as controls. Material and Methods In all, 190 patients undergoing coronary artery bypass surgery were prospectively evaluated. Patients from two subsets were included: after approval from the local ethics committee of the University of Leipzig 48 of the patients receiving MIDCABG had been randomly assigned to either robotic ITA takedown (MIDCABG-endo, n 24) or conventional MIDCABG (MIDCABG-conv, n 24). These patients gave written consent to participate in the study. The other 142 patients received routine surgical treatment, either MIDCABG-conv (n 49) or CABG-conv (n 93), as indicated by medical demands. All of these patients gave informed consent to participate in this study on postoperative pain assessment. During their preoperative and postoperative course all patients were prospectively evaluated for the study endpoints. Thus from the two subsets three groups emerged for 2002 by The Society of Thoracic Surgeons /02/$22.00 Published by Elsevier Science Inc PII S (02)

2 Ann Thorac Surg BUCERIUS ET AL 2002;73: PAIN AFTER MIDCABG 1181 further analysis within this study: MIDCABG-endo (n 24), MIDCABG-conv (n 73), and CABG-conv (n 93). The patients receiving MIDCABG-endo underwent endoscopic computer-enhanced ITA dissection through three thoracic ports using the da Vinci telemanipulation system (Intuitive Surgical, Mountain View, CA) as described previously [4, 5]. The anastomosis was performed through a conventional left anterior minithoracotomy in the fifth intercostal space on the beating heart. In the MIDCABG-conv group ITA takedown was performed under direct vision by using different rib retractors. Patients received intercostal injection of a single dose of 50 mg bupivacaine (Carbostesin; Astrazeneca GmbH, Germany) diluted in 20 ml NaCl. CABG-conv was performed in patients with two- or three-vessel disease through a median sternotomy on cardiopulmonary bypass. In all groups anesthesia was initiated with propofol (Disoprivan; Astrazeneca GmbH, Germany), sufentanyl (Sufenta; Janssen-Cilag GmbH, Germany), pancuronium bromide (Pancuronium Curamed; Curamed Pharma GmbH, Germany), and sodium thiopental (Thiopental Nycomed; Nycomed GmbH, Germany) and maintained with sufentanil (Sufenta; Janssen-Cilag GmbH, Germany) and propofol (Disoprivan; Astrazeneca GmbH, Germany) according to the standard protocol of the Department of Anesthesiology, Heartcenter, University of Leipzig. There were no differences between all groups regarding the intraoperative pain management. All patients received additional morphine-like analgesics (piritramid, Dipidolor, Janssen-Cilag GmbH, Germany; tramadol, Tramal, Grünenthal, GmbH, Germany) or nonsteroidal antiinflammatory drugs ([NSAIDs] ibuprofen, Imbun, Merckle GmbH, Germany) during the postoperative period upon demand. Assessment of postoperative pain was achieved by interview on a daily basis through POD (POD) 7. A standarized questionnaire was used [2]. All interviewers were blinded with regard to the performed surgical procedure. Furthermore, patients were asked not to talk about the operation carried out. If pain medication was requested patients were asked about the time relation between the administration and the verbal interview. In order to avoid lower pain levels due to the applicated pain medication pain levels before administration of pain medication were evaluated in cases of a short time relation. The pain questionnaire included data concerning pain intensity, character, change in pain intensity over time, localization, occurrence of pain in relation to physical activities, dosage of requested additional pain medication as well as effectiveness of pain medication [2]. Furthermore, patients were asked whether they could breathe, move and perform all other activities without any discomfort. Pain intensity was quantified using the visual analog scale (VAS) and the verbal rating scale (VRS) [2, 3]. None of the patients was on chronic pain medication preoperatively. Continuous variables are given as mean standard deviation, categorical data as proportions. Statistical Table 1. Preoperative Patient Characteristics for the Three Groups (Analysis of Variance) analysis was performed using a general linear model (GLM) for repeated measures. Preoperative and postoperative data as well as pain levels were compared using the one-way analysis of variance (ANOVA) procedure (SPSS statistical package; SPSS Inc, Chicago, IL). Results Number Male 66.7% 75.3% 75.3% Female 33.3% 24.7% 24.7% Age (years) BSA (m 2 ) EF (%) MIDCABGendo MIDCABGconv CABGconv CABG-conv conventional coronary artery bypass grafting; MIDCABG-conv left anterior minithoracotomy; MIDCABGendo internal thoracic artery dissection using an endoscopic approach; BSA body surface area; EF ejection fraction. Preoperative patient demographics are shown in Table 1. There were no significant differences between groups regarding age, body surface area and left ventricular ejection fraction (ANOVA). A total of 1,187 questionnaires was analyzed and rendered sufficient information for further evaluation of postoperative pain characteristics. Overall patient compliance was very good. With regard to additional postoperative pain medication, patients mentioned that it resulted in a sufficient relief of pain if requested. When looking at postoperative data for the three groups statistically significant differences were found with regard to total hospital stay between the MIDCABG-endo and both the MIDCABG-conv and the CABG-conv groups. However, no significant differences between the groups were found for duration of intubation, chest tube drainage, and time on the intensive care unit (ANOVA; Table 2). Pain levels (VAS) showed a significant decline in all groups from POD 1 to 7 (p in all groups; GLM). Table 2. Postoperative Data for the Three Groups (Analysis of Variance) Intubation (h) Chest tube (h) Intensive care (h) Total hospital stay (days) a b MIDCABGendo MIDCABGconv CABGconv a p 0.05 MIDCABG-endo versus MIDCABG-conv. b p 0.05 MIDCABG-endo versus CABG-conv. CABG-conv conventional coronary artery bypass grafting; MID- CABG-conv left anterior minithoracotomy; MIDCABG-endo internal thoracic artery dissection using an endoscopic approach; h hours.

3 1182 BUCERIUS ET AL Ann Thorac Surg PAIN AFTER MIDCABG 2002;73: Table 3. Pain Levels for MIDCABG-endo, MIDCABG-conv, and CABG-conv Groups on Postoperative Day 1 to 7 According to the Visual Analog Scale (Analysis of Variance) Postoperative Day CABG-conv MIDCABG-conv p a a a 0.34 CABG-conv MIDCABG-endo p a a a a a a MIDCABG-conv MIDCABG-endo p a a 0.05 a a a a p Daily pain levels according to the Visual Analog Scale are given as mean standard deviation. CABG-conv conventional coronary artery bypass grafting; MIDCABG-conv left anterior minithoracotomy; MIDCABG-endo internal thoracic artery dissection using an endoscopic approach; VAS scale range from 1 to 10: 1 no pain; 10 worst pain. The maximal pain level was observed at POD 1 in the MIDCABG-conv group. From POD 3 onward an improvement in postoperative pain was observed in all groups. Overall pain was in the range of 0 to 6 for all groups postoperatively. Significantly lower pain levels were found for MIDCABG-endo versus MIDCABG-conv (p 0.001; GLM) and for MIDCABG-endo versus CABGconv (p 0.001; GLM). Overall pain levels in the MID- CABG-conv group were slightly lower when compared with the CABG-conv group, without reaching statistical significance (p 0.138; GLM). On POD 3 through 7 statistically significant advantages with regard to pain levels were found for the MIDCABG-endo group in comparison with both the CABG-conv (p 0.05; ANOVA) and the MIDCABG-conv groups (p 0.05; ANOVA), respectively. However, on POD 1 a significant difference was found between the MIDCABG-conv and the CABG-conv groups with statistically higher pain levels in the MIDCABG-conv group (p 0.007; ANOVA, Table 3). Pain intensities for POD 2 and 7 as evaluated by the verbal rating scale (VRS) showed relatively higher pain levels in all groups on POD 2 as reflected by more patients expressing moderate, severe, and even unbearable pain in the CABG-conv and the MIDCABG-conv groups. Before discharge at POD 7 pain levels decreased in almost all cases and the majority of patients suffered no or only mild to moderate pain (Fig 1). Requirement for additional pain medication within the postoperative period was very low and a statistically significant decline from POD 1 to POD 7 was observed in all groups for each of the applied analgesics (p 0.05 in all groups for all applied analgesics). As expected, request for additional pain medication was highest on POD 1 to POD 3. There was only a little demand for pain medication after POD 3 in all groups with a tendency towards light analgesics (ibuprofen, tramadol). Furthermore, overall pain medication was low from POD 1 to POD 7 in all groups. Therefore, no statistical difference was found between the groups with the exception of the ibuprofen medication which was significantly lower in the MIDCABG-endo group as compared with the MID- CABG-conv and the CABG-conv group (p and p 0.018, respectively). In addition, piritramid medication in the MIDCABG-conv groups was significantly higher as compared with the CABG-conv group (p 0.019). Comment In an effort to minimize access in cardiac surgery, endoscopic approaches have become more popular. Several potential advantages of less invasive techniques such as reduced trauma, better cosmetic results, and shorter Fig 1. Pain levels for conventional coronary artery bypass grafting (CABG-conv) group, left anterior minithoracotomy (MIDCABGconv) group, and internal thoracic artery dissection using an endoscopic approach (MIDCABG-endo) group on postoperative days (POD) 2 and 7 according to the verbal rating scale (gray bars 5, unbearable pain; checked bars 4, severe pain; open bars 3, moderate pain; diagonal bars 2, mild pain; solid bars 1, no pain).

4 Ann Thorac Surg BUCERIUS ET AL 2002;73: PAIN AFTER MIDCABG 1183 recovery times have been shown by some [4 6]. Postoperative pain and quality of life are important end points after a surgical procedure [7, 8]. We studied postoperative pain levels after endoscopic ITA takedown compared with ITA preparation through a left anterior minithoracotomy and conventional CABG through a median sternotomy. Assessment of pain is difficult because of individual differences in pain perception. A number of scoring systems has therefore been developed allowing for a more objective assessment of pain levels [9, 10]. In agreement with recent studies we found low postoperative pain levels in all groups. Furthermore, this study confirms prior findings that pain levels decreased progressively during the first 7 postoperative days as most patients had only mild pain before discharge. High pain levels were only found on POD 1 to 3 mainly in the MIDCABG-conv group but also in the CABG-conv group. This was an unexpected finding as patients undergoing MIDCABG procedures were intraoperatively treated with anesthetic agents [2, 3]. When comparing pain levels over time (POD 1 through 7) with regard to the different surgical approaches pain was lowest in the MIDCABG-endo group and reached statistical significance in comparison with both the MIDCABG-conv and the CABG-conv groups. However, no significant differences were found between the CABG-conv and the MIDCABG-conv groups. Additional postoperative opioid medication (piritramid, tramadol) tended to be lower in the MIDCABGendo group. However, no statistically significant differences were found between the groups. NSAID medication with ibuprofen was significantly lower from POD 1 to 7 in the MIDCABG-endo group in comparison with both the CABG-conv and the MIDCABG-conv group. Overall demand for pain medication was very low in all groups and lower pain levels in one group cannot be explained by a higher pain medication with the exception of the piritramid medication in the MIDCABGconv group. Walther and associates [2] studied postoperative pain levels and quality of life after MIDCABG procedures compared with conventional coronary bypass operations. They found relatively higher pain levels in the MID- CABG group as compared with the conventional approach. These results were confirmed by recent studies by Lichtenberg and associates [11] and Trehan and associates [12]. In both studies, higher postoperative pain levels were observed in the MIDCABG groups as compared with conventional CABG through a median sternotomy and through a ministernotomy for isolated ITA dissection. Furthermore, Trehan and associates [12] found a less requirement for postoperative pain medication in the ministernotomy group in comparison to the MIDCABG group. As a consequence of these results, intraoperative injection of local anesthetic agents in the fifth intercostal space after MIDCABG was introduced [2]. However, pain levels remained still elevated after MIDCABG procedures on the first postoperative days. Therefore, intraoperative cryoablation of the fifth intercostal nerve after lateral minithoracotomy for MIDCABG or mitral valve surgery was introduced [3, 13, 14]. When compared with MIDCABG procedures with injection of local anesthetic agents we found significantly lower postoperative pain levels after intraoperative cryoablation therapy [3]. Furthermore, pain levels in the mitral valve group with anesthetic application were lower as compared with the MIDCABG group with the same treatment. The higher pain levels in the MIDCABG group can be explained by the traumatic spreading of the chest required for ITA dissection under direct vision. The current and prior studies confirm this finding [6, 15]. In a series of 44 patients undergoing video-assisted coronary bypass grafting without rib retraction for ITA harvesting the small anterior thoracotomy was well tolerated in all cases [15]. By avoiding rib retraction using an endoscopic computer-enhanced approach for dissection of the left ITA postoperative pain can be significantly reduced. Furthermore, the requirements for additional pain medication can be lowered by using this technique. In conclusion, endoscopic ITA takedown leads to significantly lower postoperative pain and thus to improved quality of life for these patients. References 1. Diegeler A, Falk V, Matin M, et al. Minimally invasive coronary artery grafting without cardiopulmonary bypass: early experience and follow-up. Ann Thorac Surg 1998;66: Walther T, Falk V, Metz S, et al. Pain and quality of life after minimally invasive versus conventional cardiac surgery. Ann Thorac Surg 1999;67: Bucerius J, Metz S, Walther T, et al. Pain is significantly reduced by cryoablation therapy in patients with lateral minithoracotomy. Ann Thorac Surg 2000;70: Falk V, Diegeler A, Walther T, et al. Total endoscopic computer enhanced coronary artery bypass grafting. Eur J Cardiothorac Surg 2000;17: Mohr FW, Falk V, Diegeler A, et al. Computer enhanced robotic cardiac surgery: experience in 148 patients. J Thorac Cardiovasc Surg 2001;121: Duhaylongsod FG, Mayfield WR, Wolf RK. Thoracoscopic harvest of the internal thoracic artery: a multicenter experience in 218 cases. Ann Thorac Surg 1998;66: Chocron S, Etievent JP, Viel JF, et al. Prospective study of quality of life before and after open heart operations. Ann Thorac Surg 1996;61: Hlatky MA, Rogers WJ, Johnstone I, et al. Medical care and costs and quality of life after randomization to coronary angioplasty or coronary bypass surgery. N Engl J Med 1997; 336: Hunt SM, McKenna SP, McEwen J, Backett EM, Williams J, Papp E. A quantitative approach to perceived health status: a validation study. J Epidemiol Comm Health 1980;34: Westin L, Carlsson R, Israelsson B, Willenheimer R, Cline C, McNeil TF. Quality of life in patients with ischemic heart disease: a prospective controlled study. J Intern Med 1997; 242: Lichtenberg A, Hagl C, Harringer W, et al. Effects of minimal invasive coronary artery bypass on pulmonary function and postoperative pain. Ann Thorac Surg 2000;70: Trehan N, Malhotra R, Mishra Y, et al. Comparison of ministernotomy with minithoracotomy regarding postoperative pain and internal mammary artery characteristics. Heart Surg Forum 2000;3: Feifel G, Schüder G, Pistorius G. Kryochirurgie Renaissance oder echter Fortschritt? Chirurg 1999;70:154 9.

5 1184 BUCERIUS ET AL Ann Thorac Surg PAIN AFTER MIDCABG 2002;73: Cheatle TR, Kayombo B, Perrin M. Cryostripping the long and short saphenous vein. Br J Surg 1993;80: Benetti F, Mariani MA, Sani G, et al. Video-assisted minimally invasive coronary operations without cardiopulmonary bypass: a multicenter study. J Thorac Cardiovasc Surg 1996;112: INVITED COMMENTARY Both early and late pain problems are among the reasons why some surgeons have abandoned the conventional MIDCABG procedure. Other surgeons continue to perform MIDCABG but combine it with endoscopic takedown of the internal thoracic artery. The present study supports the hypothesis that the endoscopic (and robotic) procedure significantly reduces postoperative pain. This is not due to the analgesic regimen because the patients who experienced the least pain also had the lowest postoperative consumption of analgesics, a fact that strengthens the conclusion of this article. Assessing pain is difficult. Although the authors have used an objective questionnaire and the VAS and VRS, there is still potential for bias depending on who is asking for enrollment and how; and also on who assesses pain postoperatively and how. In the present study this is partly overcome; for instance, the postoperative interviewer is blinded to the procedure of the patient. The study populations are also somewhat unclean, as the group with conventional MIDCABGs is a mixture of randomized and nonrandomized patients. It is not clear when the nonrandomized patients enrolled, if they were historical controls, how they were selected, and so forth. But in spite of some shortcomings in the study design, the conclusions of the paper appear to be solid: there is indeed a reduction in postoperative pain with endoscopic, robotic takedown of the LIMA. There are several reasons why this is an important paper. First, it has confirmed what everybody believed but without solid evidence: endoscopic LIMA takedown reduces pain. MIDCABG through the left anterior small thoracotomy should be combined with endoscopy. Second, the conclusions of the present paper have far wider importance than to just endoscopic surgery using robotics. Endoscopic takedown of the LIMA can also be performed by conventional endoscopic techniques. Third, postoperative quality of life is an important endpoint when different surgical techniques are evaluated; this may be even more important in the future. Some of the new minimally invasive techniques may not reduce classic endpoints such as mortality and early morbidity but may have significant influence on postoperative recovery and quality of life. And finally, improved postintervention quality of life is important when choosing between surgery or endovascular procedures. Jarle Vaage, MD Department of Thoracic Surgery Karolinska Hospital S Stockholm, Sweden jarle.vaage@ks.se 2002 by The Society of Thoracic Surgeons /02/$22.00 Published by Elsevier Science Inc PII S (02)