Left ventricular assist device (LVAD) explantation via a resternotomy may have significant morbidities. Blood transfusion and cardiac or coronary bypass graft injury can potentially be avoided by more direct and less invasive approaches.
PATIENTS AND METHODS
Six consecutive off-pump minimally invasive (MIS) HeartMate II (Thoratec Corporation Inc, Pleasanton, CA USA) LVAD explants performed between July 2008 and February 2011 were prospectively studied. Informed consent was obtained. This approach involves two incisions: (i) a 6-cm left anterior thoracotomy and (ii) a 5-cm subxiphoid incision (Fig. 1).
The median patient age was 35 years (range, 22–51 years), and patients were predominantly female (66.7%). Four patients were INTERMACS level 1 (66.7%) at the time of LVAD implant. The mean pre-LVAD left ventricular ejection fraction was 13.3% ± 6.1% (5%–20%). Table 1 summarizes the baseline characteristics. Two of these patients had their LVAD implanted using a combination of MIS incisions: a mini-J upper partial sternotomy, left anterior thoracotomy (fifth or sixth intercostal space), and a subxiphoid incision.
The MIS explant approach used relatively virgin territory and permitted minimal dissection in the previously operated field. All LVAD outflow grafts were previously placed in the right pleural cavity and wrapped with a longitudinally split dacron vascular graft to protect against injury during reentry and to minimize retrosternal manipulation with excessive cardiac compression during MIS explant surgery in these patients with intact sternum.
The preoperative computed tomographic scan confirms the location of both the left ventricular apex with the pump-inflow cannula and the outflow graft positions. The left thoracotomy incision will be centered around the former.
A felt plug is made at the start of the operation (Fig. 1).1,2 Bovine pericardium or equivalent material is sewn onto the ventricular aspect of the plug using monofilament suture. A strong silk suture sewn onto the epicardial surface of the plug facilitates retrieval if necessary.
The subxiphoid incision facilitates dissection of both the pump and driveline (Fig. 1). The Rultract skyhook retractor system (Rultract Inc, Cleveland, OH USA) lifts the lower medial costal margins away from the operating table and further helps with retrosternal dissection of the outflow graft. The dissection continues in the plane in-between the outer and inner graft, until a few centimeters from the aorta or to the point permitting safe clamping and stapling of the outflow graft.
The cardiac apex is exposed through a left anterior thoracotomy (fifth or sixth intercostal space). The incision is large enough for (i) removal of the pump inlet cannula from the silastic sleeve, (ii) insertion of the felt plug, and (iii) placement of suture ties around the plugged silastic sleeve. Cautery dissection onto and around the LVAD pump should avoid injury to adjacent abdominal organs (ie, liver, colon). The peritoneum is repaired when necessary to avoid bleeding into the peritoneum.
Low-dose heparinization achieves an activated clotting time of 250 seconds or longer. The outflow graft is clamped once the bend-relief has been removed, and the pump is turned off, with continuous hemodynamics and echocardiographic monitoring. Once the decision has been made to remove the LVAD, the outflow graft is stapled close to the ascending aorta using a vascular stapler or tied off if accessible. The stapled ends are checked for hemostasis. Sometimes it may be easier to cut the driveline before stapling.
The pump’s inlet cannula is then removed from the silastic inlet of the apical sewing cuff and simultaneously clamped using the chitwood clamp or equivalent.. A felt plug fashioned at the start of the operation is then used to plug the silastic inlet (Fig. 1). Silk ties secure the plug within the silastic inlet. Plastic cable ties can also be applied using a sterile tie gun. The pump is then removed, and the remnant driveline is dissected out and removed. Pericardial and pleural drains complete the procedure.
The median duration of LVAD support was 191 days (range, 69–307 days), with 135 days (range, 44–260 days) of median duration of home support. There was no procedural or 30-day mortality. At median follow-up of 688 days (range, 127–1033 days) after explantation, all patients are alive and free from heart failure symptoms, rehospitalization, LVAD reinsertion, or listing for cardiac transplant.
The median operation time was 203 minutes (range, 175–229 minutes). The median blood transfusion was 2.5 units (range, 1–6 units), fresh-frozen plasma use was 4 units (range, 0–4 units), and platelet transfusion was 0 unit (range, 0–1 unit). All patients were extubated on the day of explant at a median duration of 188 minutes (range, 0–352 minutes) after the procedure. The median duration of intensive care unit stay and hospitalization was 1 day (range, 1–5 days) and 4.5 days (range, 3–19 days), respectively.
One postexplant embolic cerebral infarct occurred. The patient had pump failure on the third postimplant day because of pump ingestion of the thrombus, necessitating pump exchange. She developed heparin-induced thrombocytopenic thrombosis and had a peri-implant embolic stroke. While on LVAD support, she developed recurrent gastrointestinal bleeding from a duodenal ulcer. Endoscopic biopsy diagnosed in-situ adenocarcinoma, and she subsequently underwent successful gastric resection. Myocardial recovery ensued, and she was successfully explanted after 307 days of LVAD support.
The first patient who underwent MIS explant was a 22-year-old woman with viral myocarditis and resuscitated with extracorporeal membrane oxygenation before LVAD implant via a median sternotomy. Patients with previous sternotomy and patent coronary artery bypass grafts benefit from the MIS approach for the following reasons: (i) minimizing surgical dissection to access the left ventricular apex and (ii) avoiding coronary graft injury. The patients with LVADs implanted minimally invasively were also successfully explanted through a redo-thoracotomy and subxiphoid incisions because most of the surgical dissection is directly onto the metallic pump or within the plane between the outer (graft wrapped around the outflow graft) and inner vascular grafts. The MIS LVAD implants also have less bleeding, with potentially less adhesions subsequently.
Steps taken during LVAD implant also greatly facilitate MIS explant. They comprise (i) meticulous hemostasis, (ii) avoiding peritoneal breach, (iii) outflow graft wrap, and (iv) lateral placement of the outflow graft.
Peripheral cardiopulmonary bypass (CPB) was not required in this series because surgery is well away from the recovered heart, and the potential hazards are only bleeding through the unplugged apical hole and abdominal visceral injury. Emptying the heart using CPB may potentially increase the risk of air embolism.
This series reports the successful weaning and MIS explantation of six HeartMate II patients. Although this technique seems to be a great departure from conventional wisdom and technically challenging, in practice, the contrary was found. This technique greatly simplified and facilitated the explant procedure and achieves off-pump LVAD explantation through (i) two small incisions avoiding a full sternotomy, (ii) using virgin territories in reoperative cases, and (iii) avoiding further CPB complications. It has the potential to reduce morbidity and mortality associated with device explantation in patients bridged to recovery.3,4,5 The excellent early clinical outcomes of these patients may encourage clinicians to embark on the bridge to recovery strategy.
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