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Ann Thorac Surg 2003;76:872-876
© 2003 The Society of Thoracic Surgeons
a Department of Thoracic Surgery, Royal Brompton Hospital, London, United Kingdom
Accepted for publication March 4, 2003.
* Address reprint requests to Mr Goldstraw, Royal Brompton Hospital, Sydney St, London, SW3 6NP, UK
e-mail: p.goldstraw{at}rbh.nthames.nhs.uk
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Abstract |
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METHODS: We undertook a retrospective review of our experience of mediastinal exploration by cervical mediastinoscopy with or without left anterior mediastinotomy in patients with prior sternotomy between 1980 and 2001.
RESULTS: During this period 28 patients (25 male and 3 female; mean age, 63 ± 10 years), all with prior sternotomy for cardiac surgery (14 had left internal mammary artery graft), underwent mediastinal exploration. The mean interval between sternotomy and mediastinal exploration was 7.2 ± 5.1 years. Additionally, 3 patients also had superior vena cava obstruction. Cervical mediastinoscopy was performed in all 28 patients and additionally left anterior mediastinotomy was undertaken in 7 of 28 patients (4 with left internal mammary artery graft). Indications for exploration were staging of lung cancer in 22 patients (cervical mediastinoscopy, n = 22; left anterior mediastinotomy, n = 7) and diagnostic biopsy of mediastinal mass in 6 patients (cervical mediastinoscopy, n = 6). Thorough mediastinal assessment was possible in all 28 patients. In the 22 patients with lung cancer the median number of lymph node stations sampled during mediastinoscopy was 3 (range, 1 to 5). A specific diagnosis was obtained in 16 patients (metastatic lung cancer, n = 10; lymphoma, n = 3; sarcoidosis, sinus histiocytosis, and metastatic melanoma, n = 1 each). The other 12 patients with negative findings underwent pulmonary resection and only 1 of 12 (8%) patients had unexpected N2 disease, a similar proportion to our overall experience with lung cancer. There were no operative complications.
CONCLUSIONS: Prior sternotomy for cardiac surgery does not compromise the efficacy and the safety of mediastinoscopy and mediastinotomy.
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Introduction |
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We report our experience of undertaking cervical mediastinoscopy and left anterior mediastinotomy in patients with prior sternotomy for cardiac surgery in particular looking at the issues of safety and efficacy.
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Material and methods |
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Surgical technique
The surgical techniques for both these approaches have been described in detail elsewhere [1–2, 5]. The surgical technique for cervical mediastinoscopy differs little from the standard approach. The incision is sited in between the suprasternal notch and thyroid cartilage. Dissection continues until the trachea has been identified in the midline at the thoracic inlet. The mediastinal dissection continues routinely and the previous incision does not add to the problems of dissection, as the pretracheal plane is not breached in sternotomy for cardiac surgery.
The technique for anterior mediastinotomy is also similar to the standard approach with a transverse incision in the second intercostal space just lateral to the sternum usually on the left. Particular care is needed in patients with a previous left internal mammary artery graft, which may be lying extrapericardially along the course of the phrenic nerve just anterior to hilum. Additionally as the pericardial cavity may well have been left open, the presence of patent grafts warrants extra caution in assessing the subaortic fossa and left pulmonary artery when assessing suitability for resection.
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Results |
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The nature of the previous cardiac surgery included coronary artery bypass grafting in 21 patients and in 14 of 21 of these patients, the LIMA had been used as one of the grafts. Aortic valve replacement had been performed in 4 patients and there was 1 patient with each of the following cardiac procedures: open mitral valvotomy, closure of ventricular septal defect, and reimplantation of anomalous left coronary artery.
The indications for mediastinal exploration included the staging of lung cancer in 22 patients and diagnostic biopsy of a mediastinal mass in 6 patients. Twenty-two patients presented with a confirmed diagnosis of lung cancer with computed tomography (CT) evidence of mediastinal lymphadenopathy and underwent mediastinal exploration by cervical mediastinoscopy. In addition, 7 of these patients, all with left upper lobe tumors, also had left anterior mediastinotomy and 4 of these patients had a LIMA graft at the time of their coronary artery bypass surgery. All four of these LIMA grafts were clearly seen to fill with contrast, confirming their patency, during the CT scan to assess the mediastinum. In patients for whom a mediastinal exploration was undertaken to obtain a diagnostic biopsy, cervical mediastinoscopy alone was adequate in all 6 cases. Three of 28 patients also had clinical and radiologic features of superior vena cava obstruction at the time of mediastinal exploration.
There were no intraoperative complications and all the wounds healed satisfactorily. There were no significant bleeding intraoperatively and none of the patients required any blood transfusion. No procedure-related complications were noted postoperatively.
Thorough mediastinal assessment was possible in each of the 28 cases and information obtained from mediastinal exploration was definitive in deciding their further care.
In all 28 patients the results of mediastinal exploration were definitive in deciding the treatment strategy. All 6 patients presenting with a mediastinal mass had a definitive diagnosis established from the biopsy taken at cervical mediastinoscopy (Table 1). Of the 22 patients with lung cancer, in 10 cases a diagnosis of metastatic N2 disease was established. The remaining 12 patients with lung cancer had a negative mediastinal exploration on clinical and histologic assessment and these 12 patients were considered suitable for pulmonary resection.
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Twelve of these patients in whom the mediastinal exploration by mediastinoscopy was negative went on to have a thoracotomy with full systematic nodal dissection and at the time of thoracotomy they had nodes from a median of 6 (range, 3 to 11) lymph node stations removed for histologic examination. All the frozen sections were negative and therefore pulmonary resection was performed by lobectomy (n = 7) and pneumonectomy (n = 5) with 4 left pneumonectomy and 1 right pneumonectomy. The final pTNM for the 12 patients who underwent pulmonary resections was as follows: pT1N0 in 2, pT2N0 in 5, pT2N1 in 3, pT2N2 in 1, and pT3N1 in 1. Therefore only 1 of 12 patients (8%) with prior sternotomy and lung cancer who underwent pulmonary resection turned out to have unexpected N2 disease after systematic nodal dissection.
The patient with unexpected N2 disease underwent left upper lobectomy for a bronchioalveolar carcinoma staged as pT2N2M1 tumor. He had undergone coronary artery bypass grafting using a left internal mammary artery graft 9 years earlier. Preoperative staging of the mediastinum had included cervical mediastinoscopy and left anterior mediastinotomy. Staging biopsy of lymph node stations in the paratracheal and subcarinal regions were negative as were all the frozen sections at thoracotomy. Final pathologic assessment of the resected specimen confirmed the presence a metastatic deposit in the pleural clot as well as the presence of metastatic disease in the inferior pulmonary lymph node (station 9), which is not accessible by the approaches being evaluated in this paper.
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Comment |
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Mediastinal exploration in patients with prior sternotomy for cardiac surgery may be necessary in one of two clinical settings. First, such patients may develop a mediastinal mass requiring a tissue diagnosis for the definitive treatment. Alternatively they may go on to develop lung cancer associated with CT evidence of mediastinal lymphadenopathy at some time after their cardiac surgery. Cardiac comorbidities are an important predictor of postoperative morbidity and mortality after thoracotomy for lung resection [6, 7]. Therefore in this group of patients, who have already been identified as having cardiac comorbidity requiring surgical attention in the past, exploratory thoracotomy needs to be minimized. Indeed exploratory thoracotomy in itself is associated with significant morbidity and indeed mortality. Therefore in this setting a thorough preoperative assessment of the mediastinum is crucial in as much as mediastinal involvement affects not only the possibility of complete resection but also the desirability of undertaking resection [8].
The safety of cervical mediastinoscopy both as an isolated diagnostic procedure and its role in the pretreatment staging of patients with lung cancer is well documented [1–4]. The common complications include bleeding, vocal cord paresis, pneumothorax, wound infection, mediastinitis, perforation of esophagus and tumor seeding, and very rarely death. In larger published series the frequency of these complications varies from 0.2% to 2.3% [1, 3, 4, 9]. Indeed in a series of 1,259 consecutive patients undergoing mediastinoscopy for staging of lung cancer major complications only occurred in 3 patients (3 of 1,259; 0.2%) [4]. Arterial bleeding from the innominate artery or the aorta and can be controlled with limited upper sternotomy and venous bleeding can be controlled with packing. Vocal cord paresis usually results from neurapraxia or compression of the left recurrent laryngeal nerve by hematoma and is usually temporary. The incidence of this injury has remained remarkably constant over the years at approximately 0.3%. Therefore at our institution biopsies are obtained only when absolutely necessary along the course of the left recurrent laryngeal nerve and only if biopsy samples of pathologic nodes elsewhere cannot be obtained safely. The right pleura is often seen and if breached air can be evacuated using a catheter during closure. Infection usually results from infected hematoma and therefore attention to hemostasis is necessary before wound closure. Esophageal injuries can be avoided if dissection in the right paratracheal area is not extended posteriorly.
Difficulties in performing cervical mediastinoscopy after sternotomy can be readily and easily overcome if the midline of the trachea is located at the thoracic inlet. Here the previous scar and adhesions may make it difficult to identify the midline but once this is located the dissection follows the pretracheal plane that has not been breached previously. In the series presented here all 28 patients underwent cervical mediastinoscopy without any of the complications discussed above and information gathered by this examination both clinically and histologically led to definitive treatment strategy in all patients.
The hazards of cervical mediastinoscopy in the presence of superior vena cava obstruction are often overstated. We have previously shown that as long as the surgeon maintains the midline in the approach through the mediastinum, displacing the engorged veins laterally, reliable histology specimens can be obtained safely [10]. Nonetheless certain clinical entities associated with mediastinal collateral vessels such as coarctation of the aorta, cyanotic heart disease, and suppurative lung disease are considered as relative contraindications as the risks of vascular injuries are increased [11].
It has not been our routine practice to prepare the groin before mediastinal exploration in these patients with prior sternotomy. We do acknowledge that we practice in a cardiothoracic unit and therefore cardiopulmonary bypass and cardiac surgical cover is always available. It may be safe to undertake such procedures in a unit with cardiac surgical facilities if left anterior mediastinotomy is being contemplated in the face of a patent LIMA.
The concern regarding the thoroughness of the mediastinal assessment by cervical mediastinoscopy after prior sternotomy appears not to be borne out by our experience. In the 22 patients in our series with suspected lung cancer all with prior sternotomy, in whom the mediastinal exploration was undertaken for staging purposes, the median number of lymph node stations sampled was 3 (range, 1 to 5). Furthermore fewer lymph node stations were sampled in cases where a definitive diagnosis was obtained by cervical mediastinoscopy (mean, 1.7 versus 3.2 lymph node stations) and that suggests that in cases of negative exploration all the area in the superior mediastinum were explored fully. Twelve of the patients in the series presented here, all with a negative mediastinal exploration by cervical mediastinoscopy, underwent thoracotomy with full systematic nodal dissection for intraoperative staging and had lymph nodes from a median of 6 lymph node stations (range, 3 to 11) removed for hitological examination. At our institution in all patients undergoing resection for lung cancer we routinely excise and submit separately all accessible ipsilateral mediastinal nodes for histologic examination. The thoroughness and completeness of the mediastinal assessment both by cervical mediastinoscopy and at thoracotomy in the cases presented in this series is similar to experience in general. Between 1990 and 1995 the median number of nodal stations, including N1 and N2, examined and submitted separately for histologic assessment at thoracotomy was 7 per patient (range 3 to 13) [12]. There is evidence to suggest that more recently at our institution we have evaluated the intrathoracic staging in greater detail at the N1 level as the mean number of N1 nodal stations submitted separately increased from 1.4 ± 0.9 to 2.7 ± 1.3 during the course of the previous study from our unit while the number of mean number of lymph N2 node stations removed has remained at 4.9 ± 1.2 [12].
Identification of unexpected N2 disease on the final pTNM classification is a measure of the thoroughness of assessment staging of the lung cancer. Of the 22 patients with lung cancer in this series, 10 were identified as having N2 disease and did not proceed to thoracotomy. Therefore 12 patients with lung cancer proceeded to thoracotomy and pulmonary resection and only 1 of 12 (8%) of these patients turned out to have unexpected N2 disease. This is similar to our overall experience of unexpected N2 disease on the pTNM staging despite all the previous staging modalities having been negative and clearly suggests that prior sternotomy does not compromise the thoroughness of the mediastinal assessment by cervical mediastinoscopy and anterior mediastinotomy [12].
Left anterior mediastinotomy after prior sternotomy is potentially more hazardous as the patents grafts, especially LIMA graft, may be very vulnerable. In the series reported here we did not obtain a preoperative coronary angiogram to confirm graft patency. Nonetheless all four of the LIMA graft in patients undergoing anterior mediastinotomy were seen to fill with contrast clearly during the CT scan. The value of left anterior mediastinotomy together with cervical mediastinoscopy in both staging and assessing operability the left upper lobe tumor by bidigital examination of the sub aortic fossa is well documented [5]. In the series reported here 7 of 28 patients had left anterior mediastinotomy to evaluate left upper lobe tumors and 4 of 7 of these patients had a patent LIMA graft.
Cervical mediastinoscopy remains the gold standard for obtaining diagnostic biopsies of mediastinal lymph nodes and paratracheal mediastinal masses with 100% specificity. Other, noninvasive assessment of the mediastinal lymph nodes including CT scanning and positron emission tomography (PET) in staging of lung carcinoma have been evaluated in numerous studies. A meta-analysis evaluating mediastinal nodal metastasis from nonsmall cell lung cancer (NSCLC), showed the mean sensitivity and specificity to be 60% and 77% for CT and 79% and 91% for PET scan respectively [13]. For a definitive tissue diagnosis, fine-needle aspiration biopsy of the mediastinal lymph nodes has been shown to have a sensitivity and specificity of 87% to 88% for detecting neoplasm and 82% to 83% for distinguishing benign from malignant disease [14]. Conversely the sensitivity of transbronchial fine-needle aspiration biopsy from the mediastinal lymph node for the staging of NSCLC ranged from 60% to 77% [15, 16]. Therefore at present no technique is sensitive or specific enough to change the current gold standard of cervical mediastinoscopy for mediastinal lymph node staging in NSCLC [17].
Cervical mediastinoscopy is also of value in the determination of mediastinal lymphadenopathy and mediastinal masses in other conditions such as tuberculosis, sarcoid, and lymphoma [1]. It will provide reliable histology allowing effective treatment in tuberculosis or other infectious diseases as well as obtaining bacteriologic specimens for culture. The presence of sarcoid type reactions in mediastinal lymph nodes draining primary pulmonary carcinoma may be present in 2.2% of cases and therefore a definitive tissue diagnosis of the lymph nodes is helpful in deciding when to proceed with thoracotomy [18].
The limitations of this study include the small number of patients in this series. However this reflects the relative infrequency with which at present patients with prior sternotomy need mediastinal exploration. However with time it is likely that more patients with prior sternotomy for cardiac surgery will need mediastinal exploration. Left anterior mediastinotomy is only of value in patients with left upper lobe tumor and therefore there are only a handful of these cases in this series. Finally, this is a retrospective series and as such open to all the biases levied upon all retrospective studies. Prior sternotomy has never been considered a contraindiaction to mediastinoscopy or mediastinotomy in our unit and therefore it is unliklely that any selection bias to perform these procedures has been introduced among the patients referred to us.
In conclusion, this report describes our experience of performing cervical mediastinoscopy and left anterior mediastinotomy after median sternotomy for cardiac surgery. We did not have any major operative difficulties using either of these approaches in patients with prior sternotomy and a thorough assessment of the mediastinum was possible on each occasion. Therefore we believe that prior sternotomy does not compromise the safety and efficacy of either of these approaches and they can be used safely to evaluate the mediastinum of patients with prior sternotomy presenting with mediastinal mass and lymphadenopathy.
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References |
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TopAbstractIntroductionMaterial and methodsResultsCommentReferences |
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