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MMCTS
(October 9, 2006). doi:10.1510/mmcts.2005.001206 Copyright © 2006 European Association for Cardio-thoracic Surgery Procedure Perfusion strategies for totally endoscopic cardiac surgery
a Department for Thoracic and Cardiovascular Surgery, JW Goethe University, Theodor-Stern-Kai 7, D-60590 Frankfurt, Germany * Corresponding author: * Tel.: +49-69-6301 4071; fax: +49-69-6301 5849. E-mail: Wimmer-Greinecker{at}em.uni-frankfurt.de
For most of totally endoscopic cardiac procedures femoro-femoral perfusion techniques are necessary. Use of selective bicaval as well as single venous drainage is described. Furthermore, the use of different intraaortic balloons for aortic occlusion is explained and illustrated. Advantages and disadvantages of different systems, potential pitfalls and their solutions are discussed.
Key Words: Endoaortic balloon • PortAccess cardiopulmonary bypass • Robotically assisted cardiac surgery • Totally endoscopic cardiac surgery • Vacuum assisted venous drainage
Totally endoscopic surgery has been possible since the introduction of telemanipulator systems. Since cardiopulmonary bypass cannot be established in the operative field, femoro-femoral cannulation is necessary. Therefore, peripheral cardiopulmonary bypass systems have been developed, using an endoaortic balloon clamp with the possibility of application of cardioplegia and venting of the aortic root. Percutaneous placement of a pulmonary vent as well as a coronary sinus catheter may support these cardiopulmonary bypass systems. In 1998, D. Loulmet was the first to successfully perform coronary artery bypass grafting (CABG) without opening the chest [1]. Thereafter, the surgical community created and successfully performed several new totally endoscopic cardiac procedures. Perfusion strategies to perform these procedures are presented in the following.
The complete ENDOCPB PortAccess system – MMCTSLink 111 – consists of an arterial cannula for the femoral artery, an endoaortic balloon catheter to be advanced into the ascending aorta, and a long femoral venous drainage cannula which may be placed in the right atrium. A percutaneous pulmonary vent (ENDOVENT) and a percutaneous coronary sinus catheter (ENDOPLEDGE) may be used in addition. For selective venous drainage (ASD closure, mitral surgery), a percutaneous placement of a venous drainage cannula in the right jugular vein is necessary (Video 1), performed by the anaesthesiologist prior to surgery. The pump technician is then clamping the line.
After starting the operation by dissecting the femoral vessels, a purse-string suture is placed on the femoral vein and the patient is heparinized (Video 2).
If only a single venous drainage cannula is used (in totally endoscopic CABG surgery), this is advanced into the right atrium in Seldinger technique under echocardiographic guidance and finally placed close to the orifice of the superior vena cava (Video 3). It should not be advanced too far into the vena cava, since a collapse of the vena cava is possible due to vacuum assisted suction.
An ENDORETURN arterial cannula (21 or 23 Fr) – MMCTSLink 111 – is introduced into the femoral artery after transverse incision (Video 4). A guidewire is advanced through the cannula into the descending aorta to be sure that the right lumen will be perfused and the perfusionist is checking flow resistance before going on pump.
The arterial cannula may also be placed after using a purse string on the anterior surface of the femoral artery. The authors do not advise this technique though, since peripheral vascular disease may not be judged, if the cannula is advanced blindly. After cut down of the drape, the extension of the venous line is passed through to the anaesthesiologist and connected with the jugular cannula (Video 5). The defect is re-draped for sterile purposes.
De-airing of the intraaortic balloon, introduction of the intraaortic balloon clamp into the side port and the echo of the intraaortic balloon clamp are shown in Videos 6–8.
The correlation between aortic balloon diameter and the inflation volume of the endoaortic balloon, respectively, is shown in Graph 1.
A pulmonary vent may be used additionally to unload the left ventricle. After puncture of the jugular vein and introduction of a guidewire, the ENDOVENT – MMCTSLink 111 – pulmonary vent catheter is de-aired and finally placed (Video 9).
Alternatively the ESTECH RAP cannula may be used. There the endoaortic balloon is mounted on the tip of the cannula itself, which is advanced into the ascending aorta (Video 10). This provides antegrade flow, which is more physiologic and may reduce the risk of retrograde aortic dissection.
Photo 1 shows the set-up for vacuum assisted venous drainage. The vacuum controller (Maquet, Hirrlingen, Germany) is connected to the venous reservoir, which has to be sealed. We suggest suction from 20 to a maximum of 80 mmHg.
Photo 2 shows the set-up for haemofiltration which is routinely used in totally endoscopic cardiac surgery because of the use of St. Thomas's cardioplegia. The filter (e.g. Hemofilter SH 14 – MMCTSLink 112) is positioned between the arterial line and the venous reservoir and is used pump-less at our institution.
The set-up of cardiopulmonary bypass, including vacuum controller and haemofilter, is shown in Video 11.
To provide a bloodless field in the right atrium for ASD closure the venae cavae have to be occluded. Video 12 shows how a band is placed around the superior vena cava. This is fixed transthoracically.
Anastomosis of the left internal thoracic artery to the LAD under continuous flushing of the coronary vessel with St. Thomas's cardioplegic solution is shown in Video 13. This provides a bloodless surgical field and optimises visualisation during suturing in TECAB procedures.
The mitral valve is approached through a mini-thoracotomy in the 4th intercostal space. The video camera is brought through this incision and two additional ports are placed for the instrument arms (Photo 3). Surgical assistance is provided through the incision as well.
Totally endoscopic coronary artery bypass grafting (TECAB) To achieve the benefits of both philosophies of minimally invasive cardiac surgery, the goal is to perform TECAB off pump. This has been achieved and became standard for revascularisation of the LAD with the left internal thoracic artery [2]. If more than one vessel has to be anastomosed totally endoscopically, the use of cardiopulmonary bypass is necessary. The LAD and a diagonal branch may be revascularised by a sequential graft from the left [3]. Both internal thoracic arteries may be used for grafting of the LAD and an upper marginal branch from the left, and the LAD and the right coronary artery from the right. For the rare indication of sole revascularisation of the right coronary artery, femoro-femoral bypass is necessary as well [4]. In these procedures, venous drainage can only be performed via the groin, for arterial cannulation either the ENDOCPB system or the ESTECH RAP cannula may be used. It is crucial to use St. Thomas's cardioplegia to potentially flush the coronary arteries, if venting of the aortic root is insufficient. The use of a pulmonary vent catheter, respectively, a coronary sinus catheter is routinely not mandatory. Several multi-vessel revascularisation procedures have been described, using robotic assistance through various mini-incisions. All these procedures aim for a beating heart revascularisation though.
ASD closure
Robotically assisted mitral surgery
The ENDOCPB system has two big advantages: First of all, placement of the arterial cannula in a small vessel is easy and less traumatic. Second, the intraaortic balloon may be exchanged, if it e.g. ruptures accidentally, which may happen especially in mitral surgery by placing sutures close to the aortic root. The balloon itself is less stable because it has to be re-positioned more often and requires an experienced surgeon for re-positioning. The advantage of the ESTECH RAP cannula is the good stability of the balloon, which often does not have to be re-positioned after re-inflation and may be handled even by a less experienced patient side surgeon. As a disadvantage, the more cumbersome insertion of the balloon mounted cannula has to be considered, as well as the fact that, in the rare case of balloon rupture, the entire system has to be replaced, meaning that the patient has to be weaned from bypass, which, at some stages of surgery, might create major problems.
The following pitfalls may occur. Potential solutions are discussed [7].
Aortic dissection
Balloon migration
Balloon perforation during mitral valve surgery
Kinking and obstruction of the venous cannula
Totally endoscopic coronary revascularisation on the arrested heart may be performed with an acceptable conversion rate after a steep learning curve [8]. This should not amount to more than 10% in an experienced centre. Still, a not inconsiderable part of the conversion rate results from the use of PortAccess technology [9]. Angiographic follow-up displays comparable results to conventional on-pump CABG procedures [10]. Totally endoscopic ASD closure is a procedure with a success rate close to 100%. The defect can be closed directly, or using a patch. This is the only standardised and absolutely reproducible totally endoscopic cardiac procedure to date [5]. Robotically assisted mitral surgery shows rapidly increasing numbers in the US. This is mainly due to the fact that centres were able to increase the percentage of mitral repair using a telemanipulator system. Results are absolutely comparable to the Chitwood technique, respectively, conventional mitral procedures [6].
Totally endoscopic cardiac surgery is still very demanding. Experience with femoro-femoral perfusion strategies is mandatory for most of these procedures. The use of these techniques necessitates a learning curve itself, requires an experienced surgeon on the table and a close communication between the surgeon, the anaesthesiologist, and the perfusionist. These techniques still contribute to the conversion rate of totally endoscopic cardiac surgery, which can be kept very low if all the guidelines are being followed. The success rate is additionally depending on the vascular status of the individual patient, which has to be evaluated thoroughly prior to surgery.
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