Insertion of LVAD in extraperitoneal and extra-pericardial pocket
The LVAD is then screwed to the tunneler which is brought into the incision and through the fascia just left of the midline of the pocket. The tunneler is exited through a previously created incision in the right upper quadrant between the umbilicus and anterior iliac spine. The driveline exits with the “felt” portion remaining inside, and the LVAD is situated within the pocket.
Insertion proceeds with division of the retrosternal fat and peri-thymic tissue utilizing the Bovie and clips. The pericardium is opened along the right side of the heart to the diaphragm and over the left apex, while the superior pericardium is brought over the aorta to the pericardial reflection. Pericardial stays secure the pericardium and provide exposure of the heart.
Cannulation of Aorta and Venous System
Cannulation proceeds in the usual fashion using the right atrial appendage and ascending aorta for implantation. If concomitant valve work or ASD closure is to be performed, bicaval venous cannulation of the IVC and SVC is performed. When heparinization has progressed to an ACT of 400 s or higher, cannulation of the ascending aorta at the pericardial reflection is performed, and de-airing and securing of the cannula followed by line testing is performed. Venous cannulation is performed and connected to the circuit.
The patient is placed on CPB in the usual fashion and kept warm. Volume is removed from the heart and the field is flooded with CO2.
Coring of Left Ventricle, Placement of Core Sutures, Inserting Inflow into Apex
In order to begin the coring process, the left ventricle apex is exposed and brought closer to the midline of the sternotomy. An incision in the apex is made left of the left anterior descending artery where the heart dimples. Coring proceeds with the coring knife directed toward the LV cavity (not the septum). Any large trabeculations and thrombus are removed from the ventricular cavity; next, 2–0 pledgets are placed in horizontal mattress circumferentially around the ventriculotomy (Fig. 5.2). The inflow cuff is then seated and tied into place with circumferential sutures (Fig. 5.3). BioGlue (CryoLife Inc., Kennesaw, GA) is applied to pledgets and along the inflow cuff. The cannula is inserted in the inflow housing and secured. The heart is returned to its normal position and the LVAD unit is rested into the pre-peritoneal pocket.
Placement of LV apical LVAD sutures
Securing of LVAD inflow cannula
Outflow Graft Anastomosis to Ascending Aorta
The correct length for the outflow graft is measured and cut with a bevel edge. The aorta is partially occluded with side-biting clamp aortotomy proceeds. The OG is then anastomosed to the ascending aorta with mattress sutures which are tied, and BioGlue (CryoLife Inc., Kennesaw, GA) is applied to the single-layer running anastomosis (Fig. 5.4a–c). The graft is de-aired and clamped, and the anastomosis is checked for bleeding.
(a) Side-biting clamp placed on ascending aorta for outflow graft anastomosis. (b). Evaluation of outflow graft anastomosis . (c) Removal of side-biting clamp from ascending aorta
De-airing the Device Circuit
De-airing begins when the outflow housing is opened, and the heart is filled as the perfusionist replaces volume. Ventilation of the patient proceeds, and the head of the table is moved upward as the table’s left side is tilted downward. The outflow graft is connected to the outflow housing, and a “de-airing” hole is placed in the outflow graft. The cross-clamp is kept distal to the de-airing hole on the graft (Fig. 5.5). Transesophageal echocardiography is used to monitor the de-airing process until its completion.
LVAD in pocket, outflow connected to aorta, protective graft secured over outflow graft
Inotropes are started for optimization of right heart function, and pressors (levophed and vasopressin) are titrated as necessary to maintain hemodynamic stability and mean arterial pressures of 60–80 mmHg.
Weaning from CPB and LVAD Actuation
After placement of the LVAD, weaning off CPB is performed. The HeartMate II device speed begins at 6000 RPM once the CPB flow decreases to 2 L. The cross-clamp is released from the outflow graft to allow forward flow. As CPB weans, RPM is increased to reach between 8800 and 9600 RPM. Further, de-airing occurs through the hole in the outflow graft.
TEE assesses decompression of the LV and degree of mitral regurgitation, evaluates flow across the inflow and outflow cannula, monitors for the incidence of aortic insufficiency, assesses right ventricular function, and evaluates the interventricular septum, confirming that no bowing is present. These findings are used to adjust the RPM settings of the LVAD and optimize volume status and/or increase the dose of inotropes.
Establishing of Hemostasis
It is essential that all surgical, cannulation, and anastomoses sites are evaluated, and bleeding is addressed with pledgeted sutures. Nonsurgical bleeding is surveyed until full reversal of protamine and baseline ACT are reached, as this occurs light packing and the use of hemostatic agents may aid the process. Electrocautery may be used on soft tissue, LVAD pocket, and the sternum. Examination and proper control of bleeding in the LVAD pocket should be thorough and is necessary to proceed.
If diffuse coagulopathy and excess bleeding cannot be controlled with these methods, the mediastinum can be packed, and patch is placed over the sternotomy site with the plan to return to the operating room for true closure in 24 h after adequate resuscitation and resolution of the coagulopathy. A GoreTex pericardial membrane (Gore Medical Products, Flagstaff, AZ) is sutured to pericardial edges to minimize injury at reentry during reoperation (Morgan) .
Closure of Sternotomy and Pre-peritoneal Pocket
Chest tubes are placed in the mediastinum and pleural space. Closure of the sternotomy proceeds in the usual fashion. Abdominal fascia is closed with interrupted figures of eight. The remaining layers and the skin are closed in the usual fashion.
Modifications of Technique for HVAD and HeartMate 3
For the HeartWare HVAD device and HeartMate 3, we do not create a preperitoneal pocket. The device is place intrapericardially. Thus, the sternotomy incision does need to extend beyond the xyphoid, like for HM2. Additionally, the left hemidiaphragm does need to be taken down to accomodate for the device. Unlike the HM2, where a “cut and sew” technique is used, for the HVAD and HM3, a “sew and cut” technique is employed. This involves identfying the LV true apex/dimple, marking it, placing the felt ring over it, with the center of the ring over the true apex, marking the outer portion of the ring, and then placing plegeted sutures circumferentially. After all sutures are placed, they are passed through the felt ring, the ring is seated, sutures are tied, and cut. A cruciate incision is then made in the LV apex, followed by spreading with a Tonsil clamp, followed by coring of the LV, followed by resection of LV trabeculae. The device is then inserted with the outflow graft clamped. The device is then secured in place while ensuring there is good apposition between the pump and felt ring, without a space. The device is then deaired. As side biting clamp is then placed on the ascending aorta and the proximal anastomosis is performed. For additional deairing, a hole is made in the outflow graft both proximal and distal to the clamp on the aotflow graft.
As LVADs have become more widely used, techniques have been introduced and developed to decrease invasiveness of the procedure and eliminate the need for sternotomy and/or cardiopulmonary bypass (CPB) . The following sections of this chapter will describe and compare the myriad of minimally invasive approaches to LVAD implantation and selection of outflow graft anastomosis sites in the minimally invasive approach and describe techniques used in “off-pump” LVAD implantation to avoid the use of CPB.
Minimally Invasive Approaches
The advent and successful use of minimally invasive methods of VAD implantation have the potential to improve the postoperative recovery in comparison to traditional sternotomy. Heart failure patients requiring VAD often have a host of other comorbidities such as poor pulmonary function, diabetes, malnutrition, obesity, and deconditioning that add to the risks of major surgery and can delay wound healing. The use of minimally invasive implantation therefore has the potential to decrease recovery time and avoid the stress of sternotomy.