Asian Cardiovasc Thorac Ann 2008;16:366-369
© 2008 Asia Publishing EXchange Ltd
Harmonic Scalpel in Video-Assisted Thoracoscopic Thymic Resections
Jia-Lin Soon, MRCS,
Thirugnanam Agasthian, FRCS
Department of Cardiothoracic Surgery, National Heart Center, Singapore
For reprint information contact: Jia-Lin Soon, MRCS, Tel: 65 6436 7598, Fax: 65 6224 3632, Email: soon.jia.lin{at}singhealth.com.sg, Department of Cardiothoracic Surgery, National Heart Center, Mistri Wing, 17 Third Hospital Avenue, Singapore 168752.
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ABSTRACT
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Video-assisted thoracoscopic thymectomy is safe, but the efficacy of this technique in thymomectomy is unproved. Data of 103 consecutive patients who had thoracoscopic thymectomy and thymomectomy between 1998 and 2006 were retrospectively reviewed. Conventional monopolar diathermy and endoscopic Liga clips were used in the first 50 patients, and the Harmonic Scalpel was employed in the next 53. Only mean tumor size differed between groups (56.6 ± 18.2 vs 40.0 ± 20.8 mm in Harmonic Scalpel group). A similar number of patients had myasthenia gravis in the first group (72%) and Harmonic Scalpel group (83%). There were 49 thymomas (22 in first group, 27 in Harmonic Scalpel group). Of the earlier patients, 2 were re-explored for excessive chest tube drainage, 1 had ipsilateral phrenic nerve injury, and 2 had left phrenic nerves sacrificed intraoperatively due to thymoma invasion, but there was no significant difference in complications between groups. At a mean follow-up of 3.40 ± 2.38 years (range, 0.04–8.52 years), there was 1 thymoma recurrence in the first group. Use of the Harmonic Scalpel in video-assisted thoracoscopic thymic resection is safe and confers some advantages over conventional methods of dissection.
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INTRODUCTION
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The Harmonic Scalpel (Ethicon Endo-Surgery, Cincinnati, OH, USA) uses ultrasonic energy to precisely cut and coagulate at lower temperatures than conventional electrosurgery, allowing for greater precision near vital structures. The CS14C 5-mm coagulating curved shears, resembling Kelly scissors, and curved scissors with a rotating titanium blade have been our choice for thoracoscopic thymectomies. A single multifunctional instrument holds, dissects, coagulates, and cuts (both tissue and vessel) with minimal smoke, thereby reducing the need for instrument changes. Video-assisted thoracoscopic surgery (VATS) for thymectomy is safe, but its efficacy in thymomectomy has not been proved. We reviewed our experience of VATS thymectomy and thymomectomy.
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PATIENTS AND METHODS
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There were 103 consecutive patients who underwent thymectomy and thymomectomy by a single surgeon at 2 tertiary institutions (National Heart Center at Singapore General Hospital and Tan Tock Seng Hospital) between March 1998 and March 2006. All medical records were reviewed with institutional review board and ethics committee approval. Conventional monopolar diathermy and endoscopic Liga clips were used in the first 50 patients (HS– group), and the Harmonic Scalpel was employed in the next 53 (HS+ group). The patients’ data are summarized in Table 1
. The majority presented with myasthenia gravis (MG): 44 (83%) in HS+ group and 36 (72%) in HS– group (p = 0.238), and the others had cough (1 HS+, 4 HS–) or the incidental finding of an abnormal chest radiograph. The severity of MG was graded by the Osserman-Genkins classification before resection and at the final follow-up. 1 Outcome was graded according to our simplified version of the Myasthenia Gravis Foundation of America postintervention status classification. 2
Standard lung isolation using a double-lumen endotracheal tube was instituted, with bronchoscopic confirmation of tube position. The patient was propped up 30° on the side of surgical approach, with the ipsilateral arm held in place over an L-screen, using cotton-padded crepe bandage. Three 5-mm ports were created: a central port for the 30°-angled camera, and 2 for endoscopic instruments. From March 2001, the Harmonic Scalpel was used for all surgical dissection and division of the thymic artery and veins. The ipsilateral phrenic nerve was visualized, and the contralateral pleura was opened to try to visualize the opposite phrenic nerve also. The dissection superiorly was simplified by entry into the plane deep to the pretracheal fascia after identifying the innominate vein. The superior horns of the thymus can be easily pulled down with no bleeding. We routinely removed the thymus completely, together with the anterior mediastinal and lower cervical perithymic adipose tissue, using the endobag. One port incision could be enlarged for removal of larger thymomas en mass, using only Langenbeck retractors (Figure 1).
All statistical analyses were performed with SPSS version 14.0.2 software (SPSS, Chicago, IL, USA). Results are expressed as mean ± standard deviation. Categorical variables were analysed using the chi-squared or Fisher’s exact test. The 2-sample t test or Mann-Whitney U test was used for continuous variables. A value of p < 0.05 was considered significant.
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RESULTS
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Two patients died on the 14th and 28th days postoperatively. The first was a 39-year-old lady in the HS– group with Osserman grade III MG who was re-intubated on the 4th postoperative day for myasthenic crisis, but died 10 days later. The other was a 69-year-old lady smoker in the HS+ group with 1-year history of stage IIB MG who was treated with pyridostigmine and propantheline; she was also found to have a 4.5-cm encapsulated thymoma. She was extubated immediately and transferred to the neurology service 3 days postoperatively, but died later in hospital. Operative details are given in Table 1
. The 2 intraoperative conversions to median sternotomy were for severe ipsilateral pleural adhesions and for exuberant perithymic fat on left thoracoscopy, with a concomitant 5-cm thymoma. All patients were extubated in the operating room, except for 2 in the HS– group: one ventilated for 1 day (preoperative Osserman grade III), and another for 3 days (preoperative Osserman grade IV). Three patients had bleeding complications (all in HS– group), of whom 2 underwent surgical reexploration, including 1 emergency sternotomy for repair of a left posterior descending coronary artery injury with platelet transfusion alone; another received a 250-mL blood transfusion without reexploration. One patient had his left phrenic and vagus nerves sacrificed en bloc with his 7-cm invasive thymoma, taking a cuff of pericardium. He was the patient with inadvertent coronary artery injury; he recovered uneventfully and went home on the 6th postoperative day. He was in remission after 5.22 years with reduced amounts of pyridostigmine (60 mg twice daily), without recurrence. Another left phrenic nerve was sacrificed with a 6-cm invasive thymoma; with radiotherapy, this patient was recurrence-free at 6.3 years post-resection. There were 4 (4%) superficial wound infections. A single inadvertent ipsilateral phrenic nerve injury occurred during resection of a 7-cm encapsulated thymoma (HS– group). The lady died from an unrelated cause 5.35 years post-resection. Eighty patients were identified with MG; 5 were excluded from the analysis because of incomplete follow-up records. Data were analyzed after a mean follow-up of 3.40 ± 2.38 years (range, 0.04–8.52 years). Mean Osserman grade was calculated by ascribing values: asymptomatic = 0; grade I = 1; grade IIA = 2; grade IIB = 3; grade III = 4; grade IV = 5. Tables 2 and 3 summarize the results.
All resected specimens were accepted by the pathologist with no complaints of crush or thermal-injury artifact. Of these, 49 were reported as thymomas, 26 were thymic hyperplasia (14 HS+ patients), 18 were normal or atrophic glands, 4 were thymic cysts, 2 were mature cystic teratomas, 2 were thymolipomas, and 1 was a plasma cell tumor with amyloid (1 histology unknown). The resected thymomas had a mean size of 47.41 ± 21.17 mm (range, 10–90 mm). There were 19 (39%) non-invasive thymomas; the Masaoka stages of the others were: 26 (53%) stage II, 3 (6%) stage III, and 1 intraoperatively diagnosed stage IVA. All patients with nonencapsulated thymomas were referred for adjuvant radiotherapy. The intraoperatively diagnosed stage IVA thymoma measured 60 cm; the patient was recurrence-free 5 years after resection and adjuvant radiotherapy, with remission of MG (off medication) from 1 year post-resection. Tumor recurrence was found in 2 non-MG (HS–) patients. A 76-year-old lady with a 5.5-cm Masaoka II thymoma, who declined adjuvant radiotherapy, had suspected ipsilateral pleural (diaphragmatic) recurrence with a right lower lobe nodule at 7.5 years post-resection. She remains well without therapy. The other 49-year-old man had an incidentally diagnosed 9-cm non-invasive thymoma with ipsilateral recurrence 4 years post-resection. Neoadjuvant chemotherapy followed by right extrapleural pneumonectomy was performed with adjuvant radiotherapy. Histology confirmed a WHO B3 thymoma involving the diaphragm, viscera, and parietal pleura.
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DISCUSSION
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Thoracoscopic thymectomy has been purported to achieve similar functional improvement of MG to the traditional sternotomy.3–5 Impairment of pulmonary function is less and its recovery is faster after VATS thymectomy.6 Our study confirms the safety of this approach. In this large series, there was no significant difference between use of the Harmonic Scalpel or monopolar diathermy with Liga clips, in terms of complications. There have been no bleeding complications, blood transfusion requirement, or nerve injury since we adopted the Harmonic Scalpel. Unfortunately, it is difficult for a single center to accumulate enough cases for the study to be adequately powered to show a significant difference in complications when the incidence is already low.
Overall hospital stay averaged 5.1 ± 2.4 days, partly because our patients are routinely admitted on the day before surgery for pre-anesthetic review. Surprisingly, there was no significant difference in duration of operation between the 2 techniques. In fact, HS+ patients had longer operating times, perhaps due to the 6-monthly changing of cameramen as residents rotate through the department.
In the 75 MG patients with complete follow-up records, the outcome was comparable to that of contemporary open surgical approaches.7,8 More importantly we did not find use of the Harmonic Scalpel to adversely affect outcomes. Two differences were found between groups: thymoma size and myasthenic crisis. All 5 postoperative myasthenic crises occurred in the earlier cohort of HS– patients, possibly because neurologists referred patients earlier in the later half of the study (mean MG duration in HS+ group 21.8 vs 33.6 months in HS– group; p = 0.519) and with milder (better-controlled) disease. Alternatively, it may be argued that less manipulation or more complete thymic resections were performed with the Harmonic Scalpel. In subgroup analysis, patients with thymomas were older (mean age, 51.8 vs 39.9 years in those without thymoma; p < 0.001). Thymomas appearing localized on computed tomography were selected for VATS excision. Invasive thymomas were all diagnosed intraoperatively. Thymomas were smaller with mean size < 5 cm in the Harmonic Scalpel group (p = 0.005), and there has been no tumor recurrence since its use in 2001 ( p = 0.233). Longer follow-up will be required before any conclusion can be made regarding the role of VATS thymomectomy.
Contrary to conventional thinking, this minimal access technique offers maximal exposure and visualization, facilitating complete clearance of the anterior mediastinal tissue. Use of the Harmonic Scalpel was shown to be safe and potentially more efficacious than conventional diathermy dissection. We offer this procedure to patients with MG and well-encapsulated masses, including thymomas below 6 cm in size.
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ACKNOWLEDGMENTS
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We would like to thank Ms Wong Hwee Bee, Biostatistician at the clinical trials and epidemiology research unit for statistical advice.
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REFERENCES
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ABSTRACT
INTRODUCTION
