MMCTS
(February 19, 2007). doi:10.1510/mmcts.2005.001529
Copyright © 2007 European Association for Cardio-thoracic Surgery
Procedure
Implantation technique of the Novacor left ventricular assist device
Alain Paviea,*,
Nils Reissa,b and
Stéphane Auberta
a Department of Cardiothoracic Surgery, Institut du C ur (Professor Gandjbakhch), University Pierre et Marie Curie, Paris, France
b Clinic of Thoracic and Cardiovascular Surgery, Heart Centre North Rhine-Westphalia, Bad Oeynhausen, Ruhr-University of Bochum, Germany
* Corresponding author: * Department of Cardiovascular Surgery, Pitié Salpêtrière Hospital, 47-83 boulevard de l'hôpital, 75651 Paris Cedex 13, France Tel.: +33-1-42165682; fax: +33-1-42165639 E-mail: alain.pavie{at}psl.ap-hop-paris.fr
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Summary
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The Novacor implantable left ventricular assist device has demonstrated clinical success in both the bridge-to-transplant and destination-therapy patient populations. The original clinical protocols recommended placement of the pump/energy converter within the peritoneal space. Nevertheless, during preclinical studies it was seen that it might be difficult to place this device in the peritoneal cavity of tall, slender patients, patients having a small muscular abdomen, and many women. Therefore, a technique using preperitoneal placement of the pump/energy converter was proposed. In between, this technique has been used with several modifications in more than several hundred patients worldwide. A detailed description of the insertion technique used in La Pitié, Paris, is presented.
Key Words: Left ventricular assist device • Heart failure • Bridging-to-transplant • Destination therapy
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Introduction
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The prevalence and incidence of heart failure is on the rise. Due to the lack of donor organs, cardiac transplantation can have only a minimal epidemiologic impact. Advances in left ventricular assist device development and experience with management and surgical implantation techniques have slowly improved the field, and the use of these devices to treat severe heart failure is gaining acceptance [1,2,3,4]. Patients who are selected for left ventricular assist device support must be able to undergo the surgical implantation procedure safely and avoid common complications such as right heart failure.
One of the most implanted left ventricular assist devices is the Novacor system. The original concept was to place the pump/energy converter within the peritoneal space [3]. Pump inflow would be via the left ventricular apex and the pump outflow graft would be sutured to the abdominal aorta. It was soon recognised that intraperitoneal placement of the pump/energy converter in tall, slender individuals and individuals who have a small muscular abdomen would be difficult because of the size and weight of the device. In consequence, the pump/energy converter was placed preperitoneally [3]. Because long Dacron grafts had been used successfully in aortic surgery, it was decided that the outflow graft of the Novacor device should be connected to the ascending aorta. Because of these concerns the following implantation technique was used at La Pitié in Paris.
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Surgical technique
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The patient is placed in a supine position. Peripheral intravenous, radial arterial line, and pulmonary artery catheters are placed under local anaesthesia. After induction of general anaesthesia, the patient is intubated.
The skin incision extends longitudinally from the suprasternal notch to 2 cm below the umbilicus. Sternotomy is performed prior to creation of the pocket in order to have quick access to the heart in the event of haemodynamic instability.
The preperitoneal fat is dissected from the undersurface of the rectus sheath using low power cautery. The left anterior rectus fascia is incised several millimeters from the linea alba, so that the rectus muscle is exposed. It is important not to incise the linea alba to preserve the integrity of the abdominal wall and prevent hernia formation. A plane is developed posterior to the rectus abdominis muscles. The rectus abdominis muscle has been retracted and a pocket for the pump/energy converter developed along the posterior rectus sheath. The pocket extends superiorly to the costal margin and inferiorly to the iliac crest. Laterally, it extends beyond the linea semilunaris beneath the external oblique muscle. Haemostasis is achieved with electrocautery and suture ligation. The pump is inserted in the pocket to ascertain size and position (Video 1).
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Video 1 Creation of the pump pocket by dissecting the rectus abdominis from the posterior rectus fascia.
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The aortic graft is treated with fibrin glue instead of preclotting. Thereafter the graft is tailored so that it will reach from the pump to the ascending aorta after being blindly tunnelled through the diaphragm with the aid of blunt dissection and cautery.
A partial occlusion vascular clamp is placed on the ascending aorta, and a 2-cm incision is made. The aortic graft is anastomosed end to side with 4-0 polypropylene suture (Schematic 1). The graft is clamped close to the anastomosis, the aortic vascular clamp is removed, and the anastomosis is examined for haemostasis (Video 2). We systematically apply some glue on the suture line to reduce the risk of further bleeding.
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Video 2 Anastomosis of the outflow graft on the ascending aorta.
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Preparation of the device is performed (Video 3, Photo 1).
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Video 3 Preparation of the Novacor ventricle.
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The left ventricular cannula is tunnelled through the diaphragm. The blood contacting surfaces of the pump/energy converter are primed with 5% albumin, the inflow and outflow valves are properly positioned, and the pump/energy converter is placed to the left of the midline in the previously prepared pocket. With the aid of a large metallic trocar, the vented power cable from the pump/converter is tunnelled subcutaneously across the abdomen and exits from the right upper abdominal quadrant. The use of a urinary catheter allows to prepare the tunnelisation. In fact the introduction of this catheter through the abdominal wall facilitates the introduction of the large metallic trocar. The apical and aortic conduits are connected to the pump/energy converter (Video 4).
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Video 4 Tunnelisation of the abdominal wall for the drive line.
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The patient is given intravenous heparin, 300 U/kg BW, to produce an activated clotting time of approximately 500 s. An aortic cannula is inserted in the ascending aorta near the origin of the innominate artery. Venous cannulas are positioned in the superior and the inferior venae cavae. Cardiopulmonary bypass is instituted. We do not use any kind of cardioplegia and we do not clamp the aorta: implantation is performed on beating heart. This approach allows to preserve right ventricular function. The atrial septum is inspected to rule out an atrial septal defect or a patent foramen ovale. During implantation the patient's core temperature is maintained in normothermia at 37 °C.
The patient is placed in a Trendelenburg position. The heart is retracted anteriorly, exposing the apex. Buttressed sutures (Ethibond 2-0, Ethicon) are placed circumferentially around the apical dimple and passed through the apical sewing ring. A stab incision is made in the centre of the ring. A cylindrical knife is introduced into the left ventricle. A core of myocardial tissue inside the ring is excised. This piece of muscle can be used for histological examination. The left ventricular cavity is carefully inspected. Mural thrombus and/or exuberant trabeculations that may obstruct the apical cannula are debrided. The apical cannula is inserted into the ventricle, and the pursestring suture of the apical ring is tied (Video 5, Photo 2). It is useful to use also some glue to minimise the risk of further bleeding, especially in case of acute ischaemic indication. The skirt of the apical cannula is sutured to the apical ring circumferentially by the means of 4 to 6 stitches (long needles, 32 mm). We put stitches closed to the LAD, on the right part of the ring to avoid any damage of the LAD.
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Video 5 Anastomosis of the inflow graft at the left ventricle apex.
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For deairing a 2-0 suture is placed at the upper part of the aortic graft. A vacuum line is placed in the centre of the suture (Video 6). So, this part of the aortic graft is elevated above the level of the pump/energy converter, as well as the ascending aorta. With the patient in the Trendelenburg position and with the aortic graft temporarily clamped near its anastomosis with the aorta, the device is activated on the mode single stroke, and air is vented through the graft. After all the air is removed from the device using successive clamping/declamping manoeuvres, the aortic graft is finally declamped and the system is set at a fixed rate. The flow of cardiopulmonary bypass is reduced at the same time and adequate filling of the Novacor system is verified. When stable haemodynamic conditions are obtained the Novacor system is placed in the fill rate trigger mode and cardiopulmonary bypass is stopped (Schematic 2 and Photo 3).
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Video 6 Deairing of the aortic graft.
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Results
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- The primary causes of death are sepsis (21%), multiple organ failure (18%), bleeding (15%), stroke (15%), and other (16%) [5].
- Univariate analysis of the preimplant clinical status shows that acute postcardiotomy status, respiratory failure, and right heart failure have a significant impact on 1-year survival.
- Subsequent multivariate analysis revealed that age at implant >65 years, preimplant acute myocardial infarction, preexisting right heart failure, acute postcardiotomy, and preimplant sepsis with concomitant respiratory failure are independent risk factors for survival after LVAS implantation.
- Morbidity is due to bleeding, right heart failure, bacteremia, and cerebral embolism.
- Early bleeding complications are mainly perioperative and related to the surgical procedure and hepatic dysfunction. Bleeding complications after the first month are secondary to problems with coagulation management and are manifested as digestive tract bleeding, late pump pocket bleeding, dental bleeding, and cerebral haemorrhage.
- No mechanical failure is usually encountered [6].
- During the chronic phase of support, from 3 months on, infections of the driveline exit site, device pocket, and bacteremia occur in 5% to 10% of patients. The predominant organisms cultured from driveline exit site and device pocket are Staphylococcus (46%) and Enterococcus (18%). In blood cultures, the predominant organisms are Staphylococcus (36%), Enterococcus (20%), and Candida (15%).
- In total, 75% of the time on LVAS is spent outside the hospital environment, where the majority of recipients resume their normal daily activities.
- Recently several surgical teams proposed some changes in the protocol to improve the results. A preperitoneal implantation, use of a new generation of vascular grafts, extensive drainage, and a more restricted anti-coagulation regimen improve outcome after Novacor LVAD implantation for advanced heart failure [7].
- Comparing with the HeartMate device, Novacor has fewer problems with infection and durability, and its new Vascutek conduit will reduce, but not eliminate, strokes [8].
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Discussion
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Although the majority of Novacor applications have been as a bridge to transplant, a growing number of patients are now implanted with a view to recovery of native left ventricular function. The Novacor has demonstrated a very high level of reliability and durability in the laboratory and in a wide variety of clinical settings, with no device-related failures.
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References
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- Birks EJ, Yacoub MH, Banner NR, Khaghani A. The role of bridge to transplantation: should LVAD patients be transplanted? Curr Opin Cardiol 2004;19:148–153.[CrossRef][Medline]
- Matsuda H, Matsumiya G. Current status of left ventricular assist devices: the role in bridge to heart transplantation and future perspectives. J Artif Organs 2003;6:157–161.[CrossRef][Medline]
- Pennington DG, McBride LR, Swartz MT. Implantation technique for the Novacor left ventricular assist system. J Thorac Surg 1994;108:604–608.[Abstract/Free Full Text]
- Stevenson LW, Rose EA. Left ventricular assist devices: bridges to transplantation, recovery, and destination for whom? Circulation 2003;108:3059–3063.
- Deng MC, Loebe M, El-Banayosy A, Gronda E, Jansen PG, Vigano M, Wieselthaler GM, Reichart B, Vitali E, Pavie A, Mesana T, Loisance DY, Wheeldon DR, Portner PM. Mechanical circulatory support for advanced heart failure: effect of patient selection on outcome. Circulation 2001;103:231–237.
- Pavie A, Leger P, Rabago G, Bors V, Nataf P, Gandjbakhch I. Expérience du Novacor à la Pitié. Transplantation cardiaque et pulmonaire. Les journées de la Pitié, Ed:Sandoz 1993;148–151.
- Strauch JT, Spielvogel D, Haldenwang PL, Correa RK, deAsla RA, Seissler PE, Baran DA, Gass AL, Lansman SL. Recent improvements in outcome with the Novacor left ventricular assist device. J Heart Lung Transplant 2003;22:674–680.[CrossRef][Medline]
- Navia JL, McCarthy PM, Hoercher KJ, Smedira NG, Banbury MK, Blackstone EH. Do left ventricular assist device (LVAD) bridge-to-trans-plantation outcomes predict the results of permanent LVAD implantation? Ann Thorac Surg 2002;74:2051–2063.[Abstract/Free Full Text]
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Summary
Introduction
