Eur J Cardiothorac Surg 1998;14:S148-S153
© 1998 Elsevier Science NL
Minimally invasive mitral valve surgery – clinical experiences with a PortAccess system 1
Vassilios Gulielmos*,
Jaqueline Wunderlich,
Markus Dangel,
Florian M Wagner,
Pune Karbalai,
Hermann Reichenspurner,
Sems M Tugtekin,
Stephan Schueler
Cardiovascular Institute, University Hospital Dresden, Fetscherstrasse 76, D-01307 Dresden, Germany
* Corresponding author. Tel.: +49 351 4501790; fax: +49 351 4501512.
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Abstract
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Objective: This is the initial experience with a new minimally invasive surgical technique for the treatment of mitral valve disease using a PortAccess system. Methods: Between May 1996 and May 1997, 21 patients (nine male, 12 female, aged 30–75 years, median 64 years) underwent minimally invasive mitral valve surgery. The underlying diseases were: mitral valve insufficiency (n=11), mitral valve stenosis (n=5) and combined mitral valve disease (n=5). Through a small right thoracotomy (6–8 cm) access to the pericardium and the heart was gained. Cardiopulmonary bypass was instituted through femoral cannulation and an intraaortic balloon-catheter (Heartport Inc., Redwood City, CA) was introduced for aortic occlusion, aortic root venting and delivery of cold crystalloid cardioplegia. Mitral valve repair (four patients) or replacement (15 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. There was no postoperative study-related complication. Time of ventilation, intensive care unit and hospital-stay were comparable with the data of patients undergoing conventional mitral valve surgery. Conclusions: This technique of PortAccess mitral valve surgery combines the advantage of less invasive operative trauma with the safety of conventional mitral valve surgery.
Key Words: Mitral valve surgery • Minimally invasive cardiac surgery • Endovascular cardiopulmonary bypass system • Mitral valve disease
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1. Introduction
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Recently, minimally invasive techniques have been introduced into cardiac surgery in order to avoid median sternotomy related complications such as infection, mediastinitis, nerve injuries etc. [1–8]. At the beginning coronary artery disease was the main target and single-vessel disease has been successfully treated with a variety of surgical techniques. At Stanford University a PortAccess 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 [9]. This PortAccess system has been successfully introduced in Europe in March 1996 at our institution [10]. After the initial experience with coronary artery disease this system was extended for the treatment of mitral valve disease.
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2. Materials and methods
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Between May 1996 and May 1997, 21 patients were evaluated with mitral valve diseases for PortAccess. The underlying diseases were mitral valve insufficiency in 11 patients (52.4%), mitral valve stenosis in five patients (23.8%) and combined mitral valve disease in five patients (23.8%). All patients were referred for mitral valve repair or replacement. Twelve patients were male and nine patients were female with the age ranging from 30 to 75 years (median 64 years).
The preoperative left ventricular ejection fraction ranged between 40 and 82% (median 62.0%±13%). Preoperatively 5.2% were in CCS stage 1, 31.6% in stage 2 and 63.2% in stage 3; according to the New York Heart Association (NYHA) 5.2% were in class I, 36.8% in class II, and 58.0% in class III.
Preoperative patient evaluation included transesophageal echocardiography and Doppler sonography in order to exclude major aortic valve incompetence and severe peripheral vascular disease. Overweight of more than 130%, chronic obstructive lung disease and impaired renal function were further exclusion criteria. Approval of the hospital IRB was obtained and informed consent was given by all patients.
The PortAccess technology is based on an endovascular cardiopulmonary bypass system consisting of: an endovascular aortic occlusion catheter (endoclamp) (Heartport Inc., Redwood City, CA) (Fig. 1
); a Y-shaped femoral arterial return cannula (Heartport Inc., Redwood City, CA) (Fig. 2
); a femoral venous cannula for drainage of the right atrium (DLP Inc.); an endopulmonary vent catheter (Heartport Inc., Redwood City, CA) (Fig. 3
).
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Fig. 1. Endoaortic occlusion catheter (endoclamp). The 120 cm long 10.5 F plastic flexible catheter carries at its tip a balloon for aortic occlusion. Lumen A is used for contrast medium injection (for fluoroscopy), for application of antegrade cardioplegic solution, for aortic root venting, and for active antegrade de-airing. Lumen B is used for inflating of the balloon and continuous balloon pressure monitoring. Lumen C is used for continuous aortic root pressure monitoring.
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Fig. 2. The Y-shaped arterial return cannula consists of a cannula body and an introducer for insertion into the femoral artery. The shorter proximal branch of the cannula is used for arterial return for the cardiopulmonary bypass and the longer branch is used for introduction of the endoaortic occlusion catheter.
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Fig. 3. The endopulmonary vent catheter is a 60 long 8.3 F catheter which is curved at its end for easy positioning via right jugular vein into the pulmonary artery. The catheter carries at its curved end three ventilation holes for venting.
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The endoclamp is a 120 cm long elastic curved flexible catheter with a balloon at the tip. The first catheter lumen is used for balloon inflation and for monitoring of the balloon pressure. The second lumen of the catheter allows monitoring of the aortic root pressure. The third lumen is used for contrast medium injection to secure the position of the catheter, application of cardioplegic solution and left ventricle venting during cardioplegic arrest.
Cardiopulmonary bypass was modified using a centrifugal pump (Biomedicus) for active venous drainage instead of the roller pump.
After induction of general anesthesia a double lumen tube was used in order to allow left sided single lung ventilation. A 9-F introduction sheath was placed into the right internal jugular vein for later insertion of the endopulmonary vent catheter and the right radial artery was used for invasive blood pressure monitoring perioperatively.
In 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. A 1 cm skin incision on top of the 4th rib in the anterior axilliary 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 6–8 cm (medium 7.5 cm) in the 3rd, 4th or 5th intercostal space. The pericardium was opened longitudinally anterior to the phrenic nerve and stay sutures were put thus gaining access to the heart. After systemical heparinization femoral vessels were cannulated for institution of the cardiopulmonary bypass. In 15 cases (79.0%) a 23 F-Y-shaped femoral arterial return cannula was placed into the femoral artery and in four cases (21.0%) 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 (TEE). 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 using fluoroscopy and TEE (Fig. 4
). The right radial artery pressure was monitored in order to identify occlusion of the brachiocephalic trunk in case of a balloon migration. During the insertion of the endovascular bypass system an endopulmonary vent catheter was placed by the anesthesiologist through the right internal jugular vein. Balloon pressure was monitored with a normal range from 280 to 340 mmHg. Cold crystalloid cardioplegic solution was administered and aortic root venting was made during cardioplegic arrest. The aortic root pressure was monitored simultaneously.
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Fig. 4. 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 transesophageal echocardiographic monitoring is also shown.
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Through a longitudinally incision of the left atrium access to the mitral valve was gained using an atrial retractor (Heartport Inc., Redwood City, CA) (Fig. 5
) via an additional chest port. The mitral valve was inspected and repair or replacement was performed (Fig. 6
and Fig. 7
). In all patients with mitral valve replacement the valvular apparatus was preserved. From the 15 cases in which mitral valve replacement was performed in ten cases a mechanical prosthesis of St. Jude Medical (27 mm: n=1, 29 mm: n=5, 31 mm: n=3, 33 mm: n=1) was used and in the following five cases a CarboMedics prosthesis (29 mm: n=2, 31 mm: n=2, 33 mm: n=1) was used. In the four cases of mitral valve repair the patients received a quadrangular resection of the posterior leaflet and insertion of an annuloplasty ring (28 mm: n=1, 29 mm: n=1, 30 mm: n=1, 31 mm: n=1).
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Fig. 5. The Heartport atrial retractor consisting of a retractor body lifting the roof of the left atrium (A) and the grip (B).
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Fig. 6. After placing of the sutures a mechanical valve prosthesis was inserted through the right lateral chest incision into the mitral valve annulus.
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Fig. 7. The atrial retractor (Heartport Inc., Redwood City, CA). (A) Very good access to the mitral valve. A mechanical prosthesis has already been implanted (B).
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The left atrium was closed with a continuous 4.0 Prolene suture. Before deflation of the balloon antegrade de-airing was made by active suction through the endoclamp. Additional retrograde de-airing was made. During reperfusion a left atrial catheter was placed for the monitoring of the left atrial pressure and temporary pace maker wires were placed. Intraoperative valvular function was monitored by TEE in all cases. After rewarming the patients were weaned from cardiopulmonary bypass, arterial and venous cannulas were removed and heparin was antagonized with Protamin. After hemostasis both lungs were ventilated. Two chest tubes were placed and both incisions were closed in layers. Ischemic time, time of cardiopulmonary bypass (CPB) and cardioplegic arrest, total time of surgery, time of ventilation, time on intensive care unit (ICU), and total hospital stay were monitored. As part of this study all patients had a follow-up including a wound pain assessment scale from 0 to 10 (0=no pain, 10=maximum pain), physical examinations, ECG and X-ray on postoperative day 2 and 14 and in addition patients were followed 6 and 12 weeks after surgery. The valve function was monitored postoperatively by TEE in all cases during the 3 months follow-up.
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3. Results
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Out of 21 patients which have been primarily evaluated for minimally invasive mitral valve surgery two patients had to be converted to median sternotomy, one patient due to severe adhesions of the right pleura and one patient due to paralysis of the right diaphragm which made access to the left atrium impossible. Both patients underwent conventional replacement of the mitral valve using a mechanical prosthesis (St. Jude Medical 31 mm). The remaining 19 patients underwent successful PortAccess mitral valve surgery and survived the procedure. There was no death during the whole follow-up period. 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 one were weaned from cardiopulmonary bypass without or with minor inotropic support. Due to prolonged ischemic time our first patient needed the support of an intraaortic balloon pump (IABP) in addition to low inotropic support (Dopamin 6 g) in order to be weaned from CPB. This patient was weaned from ventilation on postoperative day 3 and was discharged from hospital 16 days after the operation. Early postoperative ECG analysis showed conversion from atrial fibrillation to sinus rhythm in six patients. Intraoperative TEE and postoperative transthoracic echocardiography showed regular valve function without regurgitation in all cases but two. The first case was our first patient which was supported by the IAPB and had a small perivalvular leak. Decrease of anticoagulation for 2 weeks led to closure of the leak. In the second case after valve repair minor residual regurgitation was observed. Further complications were postoperative hemorrhage in two patients; in one patient this was anticoagulation related. The other patient underwent a reexploration and bleeding from an intercostal vessel could be identified. Additional complications are listed in Table 2
.
Technical problems of the procedure were related to the balloon of the endoclamp. In some cases we observed a balloon migration after inflation. Due to kinking of the catheter the balloon could not be deflated in one patient and had to be ruptured using a sharp wire via the Y-shaped arterial return cannula. The endoaortic occlusion catheter was exchanged and the procedure was successfully completed.
The 3 months follow-up was completed in all patients; in NYHA 57.9% are class I and 42.1% are in class II. Sinus rhythm which newly developed in six patients was maintained. The 3 months follow-up showed the continued existence of sinus rhythm.
The median pain scale (0–10) was 3.8 at the second 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.
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4. Discussion
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The present study reports our initial experience with a new surgical technique for the minimally invasive treatment of mitral valve disease. The PortAccess technique has been developed at Stanford University and has been used in a first clinical trial in March 1996 after successful treatment of coronary artery disease using the same technology. In May 1996 the PortAccess technique was started as the initial European trial successfully at our institution for the treatment of mitral valve disease. Experience of our first 19 patients is presented in this report.
Although there was a learning curve our results were encouraging. There was no mortality and despite prolonged operation time the postoperative morbidity was low. The patients recovery was uneventful and the analysis of postoperative pain revealed rapid release and the overall return to normal life activity was smooth.
The PortAccess technology has some complicated aspects such as the introduction and the placement of the endoaortic balloon catheter and its intraoperative monitoring, however with careful handling and under control of the transesophageal echo and fluoroscopy, the new generation of endoaortic clamps lost their complexity. We found that if the surgeon will not touch the heart until the whole cardioplegic solution is given and waits a few seconds after beginning of aortic root venting, once the balloon has found its right position then it will not migrate. In contrast to the experience by others [11]and in contrast to our own experience in patients undergoing CABG we have not observed any serious vascular complication related to the device such as aortic dissection in the present patient group, however, antegrade perfusion and central cannulation, introduced by our own group for minimally invasive coronary artery surgery recently seems to be more safe and easier to apply.
Different approaches of aortic cross-clamping such as direct clamping through transthoracic clamp were used successfully by others [12]and in our own series we experienced this technique in one patient. This approach could be considered as a reasonable alternative to the use of the endoaortic balloon catheter.
Patients with severe adhesions of the right pleura, small femoral vessels, or paralysis of the right diaphragm should be excluded from any minimally invasive surgical technique for the treatment of mitral valve disease.
Despite the limited skin incision (Fig. 8
) an excellent view of the mitral valve is possible and not only valve replacement procedures including preservation of the subvalvular apparatus are feasible, but also complicated mitral valve repair techniques can be applied. It may look awkward that out of 11 patients with mitral valve insufficiency only four repairs were made. The explanation is that most of these cases were heavily calcified and a repair did not seem to be appropriate. Further experience is needed to compare the results obtained with the standard sternotomy approach for the treatment of mitral valve disease and a randomized trial is planned at our institution in 1998. However, in general according to our early experience the PortAccess technique presents a safe alternative technique for the surgical treatment of mitral valve diseases with excellent results and very low morbidity.
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Footnotes
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1 Presented at the World Congress on Minimally Invasive Cardiac Surgery, Paris, May 30–31, 1997. 
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Top
Abstract
1. Introduction
