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Eur J Cardiothorac Surg 1998;14:141-147
© 1998 Elsevier Science NL

Clinical experiences with minimally invasive mitral valve surgery using a simplified port access^TM technique¹

Cardiovascular Institute, University Hospital Dresden, Fetscherstrasse 76, D-01307 Dresden, Germany

Received 29 December 1997; received in revised form 20 April 1998; accepted 28 April 1998.

Corresponding author. Tel.: +49 351 4501801; fax: +49 351 4501802.

	Abstract

Top Abstract Introduction Materials and methods Results Discussion Appendix A. Conference... References

 
Objective: Using the initial experiences with the Port-Access^TM technique for the treatment of mitral valve disease some changes were made thus resulting in more simple and faster procedures. Methods: Twenty-nine patients (13 male, 16 female, aged 30 to 75 years, median 62.5±11.0 years) underwent minimally invasive mitral valve surgery between May 1996 and December 1997. The underlying diseases were: mitral valve insufficiency (n=16), mitral valve stenosis (n=7) and combined mitral valve disease (n=6). Through a small right thoracotomy (5–7 cm) access to the pericardium and the heart was gained. Cardiopulmonary bypass was instituted through femoral cannulation and an intraaortic balloon-catheter was introduced for aortic occlusion, aortic root venting and delivery of cold crystalloid cardioplegia. Mitral valve repair (five patients) or replacement (24 patients) was performed. Results: There was no death during the whole follow-up period. There was no perivalvular leak and only minor residual mitral valve regurgitation was observed on intraoperative or postoperative (3 months) transesophageal echocardiography in three patients. There was no postoperative study-related complication. Time of ventilation and intensive care unit were comparable with the data of patients undergoing conventional mitral valve surgery but hospital stay was shorter in the last 10 consecutive cases. Conclusions: This simplified technique of mitral valve surgery combines the advantage of less invasive operative and good cosmetic results with the safety of conventional mitral valve surgery. At our institution this technique presents in well selected patients suffering from mitral valve disease the procedure of choice.

Key Words: Minimally invasive cardiac surgery • Endovascular cardiopulmonary bypass system • Mitral valve disease

	Introduction

Top Abstract Introduction Materials and methods Results Discussion Appendix A. Conference... References

 
If median sternotomy presents a common and easily made surgical gate due to the frequency of its performance, complications related to it such as infection, mediastinitis and nerve injuries are more frequent (sometimes depending on the evaluation [1] [2] [3] [4] [5] [6] [7] [8]). Trying to avoid sternotomy related complications in order to secure early rehabilitation after cardiac surgery minimally invasive surgical techniques have been developed. At the beginning coronary artery disease (CAD) was the main target and single-vessel disease has been successfully treated with a variety of surgical techniques [9] [10] [11] [12] [13] [14]. At Stanford University the Port Access^TM system has been developed including an endovascular cardiopulmonary bypass system with cannulation of the femoral vessels, and an endovascular balloon catheter for aortic occlusion, administration of cardioplegia and volume unloading of the left ventricle [15]. The same system has been successfully introduced in Europe in March 1996 at our institution [16]. The initial results achieved using this technique for coronary artery bypass surgery were promising so that we extended the application of this system for the treatment of patients suffering from mitral valve disease.

	Materials and methods

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Thirty-one patients with mitral valve diseases were evaluated for minimally invasive surgery between May 1996 and December 1997. Among them 17 patients (54.8%) out of this group were suffering from mitral valve insufficiency, seven patients (22.6%) from mitral valve stenosis and seven patients (22.6%) from combined mitral valve disease. All patients were referred for mitral valve repair or replacement. Fourteen patients were male and 17 patients were female with ages ranging from 30 to 75 years (median 62.0±11.0 years).

Preoperatively, 13 patients (41.9%) were in Canadian cardiovascular society (CCS) stage 2, 17 patients (54.8%) in stage 3 and one patient (3.3%) in stage 4; in New York Heart Association (NYHA) class I there was 1 patient (3.3%), in class II 10 patients (32.2%), and in class III 20 patients (64.5%).

Transesophageal echocardiography and Doppler-sonography were used in order to exclude patients with major aortic valve incompetence and severe peripheral vascular disease. Further exclusion criteria were being overweight by more than 130% (BMI), chronic obstructive lung disease, impaired renal function, and left ventricular ejection fraction (LVEF) under 40%. LVEF ranged between 40% and 82% (median 61.0%±11.4%). Approval of the hospital IRB was obtained and informed consent was given by all patients.

The most important component of the Port Access^TM technique is the endovascular cardiopulmonary bypass system of Heartport:

• an endovascular aortic occlusion catheter (endoclamp)
  
• a Y-shaped femoral arterial return cannula
  
• a coronary sinus catheter
  
• a femoral venous cannula for drainage of the right atrium
  
• an endopulmonary vent catheter.
  

Endovascular aortic occlusion catheter
The 120 cm long elastic, curved, flexible, multilumen catheter so-called endoclamp carries a balloon at its tip. One catheter lumen is used for balloon inflation or deflation and for continuous monitoring of the balloon pressure. Another lumen allows continuous monitoring of the aortic root pressure. A 3rd lumen is used for contrast medium injection to secure the position of the catheter fluoroscopically, antegrade application of cardioplegic solution, left ventricle venting during cardioplegic arrest, and antegrade de-airing before deflation of the balloon.

In our initial cases a centrifugal pump (Biomedicus) was used for active venous drainage for cardiopulmonary bypass. In recent cases the use of a rigid reservoir in combination with a roller pump enabled a smooth active venous suction and the biomedical pump was abandoned thus reducing the costs and simplifying the method.

In general anesthesia a double lumen tube enabled left sided single lung ventilation in order to allow transpleural access to pericardium. Changing the sequence of the procedure and first initiating CPB single lumen endotracheal tube is appropriate and easier. A 9-F-introduction sheath placed into the right internal jugular vein for later insertion of the endopulmonary vent catheter is not used any more since endopulmonary venting showed not to be as efficient as promised. The right radial artery was used for invasive blood pressure monitoring perioperatively. Antegrade application of cardioplegic solution requires no insertion of a coronary sinus catheter.

In the supine position the right shoulder and the right arm were elevated. The patient was draped with the right chest wall accessible as well as the sternum, in case the patient needed to be converted to median sternotomy. Both groins were prepared for surgical access. The femoral vessels were dissected for arterial and venous cannulation. In our first series a 1 cm skin incision on top of the 4th rib in the anterior axillary line was made for insertion of the thoracoscope into the right pleura while the right lung was deflated. After thoracoscopical inspection of the operative field the skin incision was enlarged up to 5–7 cm (medium 7.5 cm) in the 3rd, 4th, or 5th intercostal space. Moving the skin incision medially (2 cm away from the sternal edge) in order to shorten the distance between surgical incision and heart, the right arm was attached to the body dorsally to the posterior axillary line. After systemical heparinisation femoral vessels were cannulated for institution of the cardiopulmonary bypass. In 17 cases (58.6%) a 23 F-Y-shaped femoral arterial return cannula was placed into the femoral artery and in 12 cases (41.4%) a 21 F-catheter was used. Using an 100 mm guide wire a 21 F-venous cannula was inserted via the femoral vein into the right atrium, using transesophageal echocardiography. Before initiation of cardiopulmonary bypass the endoclamp was positioned in the ascending aorta 2–3 cm above the aortic valve using a guide wire via the arterial return cannula. The correct position was monitored in the first cases using fluoroscopy and transesophageal echocardiography (TEE) ( Fig. 1 ). The right radial artery pressure was monitored in order to identify occlusion of the brachiocephalic trunk in case of a balloon migration. In recent cases the position of the endoclamp was monitored using only TEE ( Fig. 2 ) and blood pressure measured via the radial artery in order to simplify the procedure avoiding fluoroscopy. On bypass longitudinally opening of the pericardium anterior to the phrenic nerve and stay sutures gave access to the heart. Intraaortic balloon inflation occluded the ascending aorta. The range of the balloon pressure was 280–340 mm Hg. Cold crystalloid cardioplegic solution was administered and aortic root venting was made during cardioplegic arrest. The aortic root pressure was monitored simultaneously.

View larger version (115K): [in this window] [in a new window]   Fig. 1. Fluoroscopic monitoring of the position of the endoarterial occlusion catheter. The inflated balloon occludes the ascending aorta. The positioning of the venous drain catheter as the position of the transducer for tranesophageal echocardiographic monitoring is also showed.

View larger version (93K): [in this window] [in a new window]   Fig. 2. TEE picture of the inflated balloon (A) 2 cm from the aortic valve (B).

View larger version (125K): [in this window] [in a new window]   Fig. 3. A mechanical prosthesis is about to be inserted through the small surgical incision into the mitral annulus.

	Results

Top Abstract Introduction Materials and methods Results Discussion Appendix A. Conference... References

 
Out of 31 patients been evaluated for minimally invasive mitral valve surgery two patients had to be converted to median sternotomy. In the first case severe adhesions of the right pleura and in the 2nd patient paralysis of the right diaphragm which was practically between the surgical incision and the pericardium made access to the left atrium impossible. Both patients underwent successful conventional mitral valve surgery. The remaining 29 patients underwent successful Port Access^TM mitral valve surgery and survived the procedure. During the whole follow-up period there was no death. The median values of aortic occlusion, CPB, time of operation, total ventilation, ICU-stay, and hospital stay are listed in Table 1. All patients except the first one were weaned from cardiopulmonary bypass without inotropic support. Due to prolonged ischemic time this first patient needed the support of an intraaortic balloon pump (IABP) in addition to inotropic support (Dopamin 6 ). On postoperative day 3 this patient was weaned from ventilation and was discharged from hospital after 16 days. Postoperative ECG analysis showed conversion from atrial fibrillation to sinus rhythm in seven patients. Intraoperative TEE and postoperative transthoracic echocardiography showed regular valve function without regurgitation in all cases but three. In two cases after valve repair minor residual regurgitation was observed. The other case was the first of our series needed intraoperatively the support of IABP. A minor perivalvular leak was treated conservatively and was disappeared in the 3-months-follow-up. Postoperative hemorrhage in two patients were further complications; in one patient this was anticoagulation related. Using the same surgical incision the other patient received a reexploration and bleeding from an intercostal vessel was identified. Additional complications are listed in Table 2.

The 3-months-follow-up was completed in 19 patients; in NYHA class I are II patients (57.9%) and in NYHA class II are eight patients (42.1%). Sinus rhythm newly developed in seven patients maintained. The 3-months-follow-up showed further existing of sinus rhythm in all cases where a convertion from atrial fibrillation was showed.

The median pain scale (0–10) was 3.8 at the 2nd postoperative day, 2.0 after 2 weeks of surgery. At the 6- and 12-week-follow-up all patients except one were completely free from any pain. This single patient had minor pain during body exercise.

	Discussion

Top Abstract Introduction Materials and methods Results Discussion Appendix A. Conference... References

 
A surgical team at Stanford University developed the Port Access^TM technique working on an experimental model and performing coronary artery bypass surgery through small thoracic port incisions [9] [15]. The first clinical trial at the same University was successfully started using this technique for the treatment of coronary artery single vessel disease. The same surgical team completed a further experimental series using the same technique for mitral valve surgery [19]. After the first successful treatment of mitral valve disease using this technique, successful use of the Port Access^TM technique commenced in May 1996 at the initial European trial at our institution. Comparing the results of our first cases with those of the recent cases, it becomes clear that a learning curve was involved (Table 1). There was no mortality and except for the first patient who was supported with an intraaortic balloon pump during prolonged ischemia time, in the remaining cases the postoperative morbidity was low even though the operation time was prolonged.

The technology used had some complicated aspects such as the introduction and the positioning of the endoaortic balloon catheter and its intraoperative monitoring; however with careful handling under control of the transesophageal echo, the new generation of endoaortic clamp lost its complexity.

Careful patient selection and exact preoperative evaluation of the vessels can avoid unpleasant surprises as aortic dissections due to the retrograde perfusion which results from femoral institution of CPB as described [16] [17]. Patients with peripheral vascular disease should be excluded from this technique. Gaining experience with this method it seems that the use of fluoroscopy is not obligatory but further simplifies the technique. In our own series we successfully experienced another technique of aortic cross clamping, such as the technique of direct clamping using a transthoracic clamp, as proposed by Chitwood et al. [18]. We consider this approach as a reasonable alternative to the use of the proposed endovascular bypass system. Paralysis of the right diaphragm or severe adhesions of the right pleura in addition to small femoral vessels should be exclusion criteria for any minimally invasive surgical approach for mitral valve surgery, as we experienced on two occasions. The endovascular bypass system in addition to the new thin and long endoscopical surgical instruments used for this surgery allow very good access to the mitral valve despite the small surgical incision ( Fig. 4 ), and make uncomplicated repair or replacement procedures including preservation of the subvalvular apparatus feasible. In well selected patients the Port Access^TM technique presents a safe alternative technique for the surgical treatment of mitral valve disease to the standard sternotomy approach. The surgical results are equal, median sternotomy related complications are completely out of consideration, and in case of future re-do operation on the same patient median sternotomy does not carry the same complexity of a re-do operation after a median sternotomy procedure. Postoperative morbidity is very low and cosmetic results are far better. The patients' recovery is uneventful and the analysis of postoperative pain reveals rapid release and what is most important the overall return to normal life activity is smoother and faster. At our institution this technique is considered to be in younger well selected persons, where cosmetic aspects are important, the procedure of choice.

View larger version (158K): [in this window] [in a new window]   Fig. 4. In female patients scars left after Port-AccessTM surgery cannot to be seen after moving the skin incision more medially.

	Footnotes

	Appendix A. Conference discussion

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Dr J. Bergsland (Buffalo, New York): I seem to remember that in Prague last year, when these results were presented in the Heartport meeting that there were some cases of dissection of the aorta from the endoclamp. Or were these earlier patients from a different institution?

Dr Gulielmos (Dresden, Germany): You have probably mixed me up with somebody else. He is standing in front here. The name is Professor Mohr, coming from Leipzig.

Dr Bergsland: So your answer is that you never had this problem.

Dr Gulielmos: We did not have any dissections in our mitral series.

Dr Friedrich W. Mohr (Leipzig, Germany): We started this in Europe together, and we have similar experiences. They did more coronaries. We did many more mitral valves, in 80 patients. And I think it is important for this meeting that we comment on this in many respects.

We had in 80 patients, three aortic dissections. One patient died of that. I think the reason for the aortic dissection is two-fold. One is the retrograde perfusion which let the dissection grow from the iliac arteries to the ascending aorta, and the other reason is the installation of catheters and guide wires at the site of the femoral artery which may create a minimal intimal tear and then you start the extracorporeal circulation and the dissection grows retrogradely.

I think this is a severe problem which has to be overcome. And if you allow me, I would like to comment a little bit more on possible results which you can achieve if you really concentrate on this technique.

In our series now we have an operation time of 2 h, a cross-clamp time of about 36–45 min for both mitral valve repair and mitral valve surgery. We minimize the incision down to 4 cm in all patients. And we minimize the surgical team to solo surgery, only one surgeon, that's me, and the other one is a mechanical arm who holds the retractor and a robotic arm which guides the 3D video camera. That only shows you how you can develop this technique, it does not show you how to overcome the severe complications which you have in both mitral valves and coronaries because of the retrograde flow and the catheters.

If there is a chance to get the arterial return into the ascending aorta, I think we can overcome the problem of aortic dissections. In my experience I think it is the surgery of choice for young patients. We had a prospective trial in our last 25 patients, dating back from July to now, and if you compare these patients to conventional surgery, these patients really do better in intensive care unit stay and pain. But the patients who had aortic dissection, the last one was last week, of course did not do better. I think we have to work very hard to overcome this problem.

You can perform the whole surgery endoscopically now if you are trained in that and you can minimize the surgical approach. Dr. Carpentier addressed it today, that this type of surgery should not be started now by everybody. Only few centers should develop it and then decide which is the way to go.

I have a question for you also. We have encountered the problem with balloon migration, and I know you did also. Once in a while the balloon tends to migrate either to the aortic valve or to the truncus brachiocephalicus. It is difficult to monitor this when you are in the middle of the operation. We did see four patients who had transient hemiparesis, and we suspect that it is due to the balloon migration to the truncus.

Did you see something like that also?

TEE does not help because as soon as you open the left atrium, you cannot monitor the ascending aorta anymore. Do you have any tricks that can help?

Dr Gulielmos: Maybe I should add at first one comment concerning vascular complications and retrograde dissections. You have to admit you yourself did not have any dissections in the past 30 cases or 40 cases or something. And I think this is due to the new generation of the catheter. Still, it is my information that the company works on improving these materials and even changing the institution of CPB.

But regarding your question, I am going to answer to you with a question. You asked for a tip. Do you notice when you have the migration of the endoclamp? I think the migration of the endoclamp happens just at the beginning. We apply antegrade cardioplegia and then we use the aortic root venting. If the endoclamp stays put at this period, and we apply the cardioplegia and the heart is arrested, then we start venting, and then we still do not touch the heart. And it is my feeling that if the intra-aortic balloon stays firm during this first 10–20 s, then it will not migrate during the whole operation.

Dr. Mohr: Quick answer. I think it migrates only in young patients, this is my experience, who have a more flexible, distendable aorta. I do not know when, sometimes in the middle of the procedure.

Dr Jean Bachet (Suresnes, France): I have absolutely no experience of such a system and I must say that I am rather reluctant to use any. Nevertheless I would like you to comment on two questions:

Firstly, I am convinced that, in this audience, a lot of colleagues have performed mitral replacement or repair through conventional right thoracotomies. So my first question is, what is the difference between a 7 cm thoractomy and a 15 cm thoracotomy that allows you to perform a perfect conventional mitral valve repair without all those tubes and devices put into the aorta through the femoral vessels and leading to those many complications?

(Applause)

My second comment, I am sorry for the success, I did not expect that, is that it is the fashion now to consider hospital costs in terms of hospital stay. Everybody in medical economics knows that what is costly during hospitalization, is the operation and the intensive care stay, not the days after. These represent almost only `hotel' spending. So have you taken into account the fact that with this technique you replace the hotel spends but you add to the costs of the conventional procedure something like $6000, that is about 8000 Deutschemarks. Is this really a reducing in cost?

Dr Gulielmos: First, to your first comment. I think I am supposed to be the one to ask you the question, because you did the 12 cm thoracotomy, and you dropped it, not me. I think this is a very good procedure. This gives you very good access to the mitral valve. And you should tell me why you stopped doing this and changed to median sternotomy? Was it the difficult access? Was it the fact that you did some thousands of times median sternotomy and you feel a lot more confident doing it?

The cost concerns, I do not see the way you do. Because you are referring to absolute hospital costs. I am referring to General costs. Because a patient receives mitral valve surgery, after being discharged from the hospital, this does not mean that he is able to go back to work. It takes him some time and we found that patients receiving this procedure go a lot faster and smoother back to normal life, and I think that is what really reduces cost.

Randolph Chitwood (Greenville, North Carolina): I have operated on 45 patients totally video assisted, using a transthoracic clamp. I have some experience in doing this technique. I think there is one concern that we need to address as academic surgeons: we need to be concerned about dissections and be very clear that if you do enough of these using retrograde perfusion you will have a dissection, no matter which version of cannula. So I think we all have to be very cautious about this potential problem.

I presented my work at the AATS this year and was pleased to say that I had not had a dissection. But not too long after that I had a dissection. So there is no question, no matter which technique you use, there is a risk.

The question I have for you is the number of mitral valve repairs that you did. There is mitral valve repair and then there is complex mitral valve repair. So to what level were you able to take your mitral valve repair technique? I clearly believe that the operation is the repair and not the technique. Thank you for allowing me to discuss this paper.

Dr Gulielmos: Most mitral valves were very calcificated. Furthermore we have not got a large experience, these are only 27. We evaluated only 27 patients for this kind of surgery. So we expect first to have very good results with straightforward patients, with mitral replacements. Of course, if we open up and we found that a repair could be done, then we just go ahead and do it.

Dr Chitwood: Do you see that you can do a Barlow's using this technique, a very complex Barlow's?

Dr Gulielmos: I have not tried it yet.

	References

Top Abstract Introduction Materials and methods Results Discussion Appendix A. Conference... References

 

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Vassilios Gulielmos Florian M. Wagner Stephan Schueler Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gulielmos, V. Articles by Schueler, S. Search for Related Content PubMed PubMed Citation Articles by Gulielmos, V. Articles by Schueler, S.