Left Ventricular Assist Device Insertion Technique

Updated: Jul 06, 2016
  • Author: Craig H Selzman, MD, FACS; Chief Editor: Karlheinz Peter, MD, PhD  more...
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Technique

Approach Considerations

Although individual surgeons and centers employ different methods to insert a left ventricular assist device (LVAD), the fundamental concepts remain true for all. That is, most devices use the apex of the left ventricle (LV) as the inflow site to the pump, which subsequently gives off an outflow graft to the aorta, thus bypassing the ailing LV. Currently available devices do not differ significantly with regard to general implantation technique. The sequence of implantation can vary also from patient to patient, depending on the particular situation. In some cases, concomitant procedures may be performed in conjunction with LVAD implantation without adversely affecting outcome. [12]

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Insertion of LVAD

After induction of anesthesia, placement of monitoring lines, and patient positioning, a median sternotomy is performed. In many cases, this is a redo sternotomy. If the patient has a hostile mediastinum (eg, from multiple or recent surgical procedures, congenital heart disease, enlargement of the right ventricle [RV], or substernal grafts), alternative forms of cannulation for cardiopulmonary bypass should be considered.

Arterial inflow can be accessed through the subclavian or femoral arteries. The authors usually sew a side-armed graft on the vessel. Venous return is through a long femoral arterial cannula placed under the guidance of transesophageal echocardiography (TEE) with the tip in the superior vena cava (SVC).

Before full heparinization and sternal reentry, many surgeons try to develop the LVAD pocket. Full creation of the pocket is made easier when the sternum is open. There are two schools of thought regarding pocket location: one prefers the pocket to be within the preperitoneal space, whereas the other prefers it to be between the posterior rectus sheath and the rectus abdominis.

For the larger pumps, the latter location was routinely chosen so as to avoid peritoneal erosion. However, for the smaller pumps, which require smaller pockets, many surgeons have gone back to the preperitoneal approach just over the diaphragm. Most surgeons take down the anterior slip of diaphragm laterally to allow the inflow cannula to orient correctly. Either an electrocautery or a vascular endoscopic stapler can be used to divide this muscle. It is important to check this transection line before closure; it often has points of bleeding.

Most devices come with a manufactured model to allow accurate sizing. To assist with sizing, the pericardium is opened and the LV apex identified. One of the useful features of the HeartMate II device is its inflow elbow, which theoretically allows good placement without the need to develop the pocket as far laterally.

The prospective site for driveline exit is then identified. It is usually in the typical right upper quadrant position but may vary according to the patient’s need. A tunneling device is brought through the right rectus sheath. Sufficient subfascial dissection should be performed on the right side to allow tension-free closure as well as provide space for driveline exit. At this point, the authors typically go into the left pleural space and place a 28-French soft Silastic tube in this cavity; once the LVAD is in place, getting back into this space is more difficult.

On the back table, the pump is prepared according to the manufacturer’s instructions. Some outflow grafts require preparation. Some devices require reinforcement, whereas others are ready to go when taken out of the package. Individual pump preparation is beyond the scope of this article, especially in view of the excellent training provided by all of the device manufacturers with regard to their respective pumps.

After heparinization and before significant manipulation of the heart, the authors place cannulation sutures in the ascending aorta and the right atrial appendage. The latter suture can then be retracted inferiorly to expose the touchdown spot on the proximal lateral ascending aorta. The HeartMate II outflow, as opposed to the HeartMate I outflow, does not easily pass out into the right chest. Consequently, a more anterior aortotomy may be required, with the graft passing over the anterior atrioventricular groove or over the RV.

With the model in place, the outflow graft is stretched and cut to size with a slight bevel. The authors place a bulldog clamp on the bend relief to keep it out of the way. After the touchdown spot is marked with a marking pen, a side-biting aortic cross-clamp is placed. An aortotomy is created with a No. 11 scalpel and opened with Potts scissors. The two ends are rounded with a 4.5-mm proximal coronary punch.

The distal anastomosis may be sewn with any of a number of techniques. Some surgeons place individual pledgeted mattress or continuous sutures over felt or pericardium. The authors typically place 4-0 polypropylene sutures at the heel and toe and run them down each side toward each other. After removal of the cross-clamp, hemostasis is checked, and repair sutures are placed as necessary.

Aortic and right atrial cannulas are placed; the authors often place an aortic vent needle as well. The patient is placed on cardiopulmonary bypass and maintained at normothermia. As mentioned above, even via a median sternotomy, this procedure can be performed without the use of cardiopulmonary bypass. That said, most centers do perform the remainder of the operation with the patient on bypass.

The heart is elevated with the assistance of laparotomy packs in the posterior mediastinum. The left anterior descending artery is identified, thus marking the intraventricular grove. A silk suture is placed in the epicardium of the site of the core; the suture is brought through the coring knife.

With larger ventricles, identification of the apex is fairly straightforward. With smaller ventricles, some surgeons core a little further anteriorly to provide a reasonable angle. The core is excised. The LV cavity is inspected, and further debridement of trabeculae or thrombus is performed as necessary. The alignment along the interventricular septum is also examined.

Large full-thickness pledgeted sutures (the authors use polyester; others use polypropylene) are then passed. The sutures are placed in a mattress fashion to catch the edge of the epicardium. Most surgeons use 12-14 sutures, though some use fewer. The sutures are attached to the sewing ring and tied. The authors often put a very thin layer of surgical adhesive (eg, BioGlue; CryoLife, Atlanta, GA) over the insertion site and pledgets.

The prospective driveline site is cored, and the tunneling device is passed subcutaneously and through the rectus at the inferior right margin of the incision. The controller and pump are brought to the table. The driveline is passed and connected to the controller. During this time, the authors insufflate carbon dioxide into the LV cavity to evacuate air.

The inflow stabilizing ring is removed. The LV cavity is inspected to make sure that the inflow is clear. The inflow cannula is inserted and secured with the sewing rings suture. The authors use two tie bands to secure the cannula further; others place several large suture ties.

At this point, the anesthesiologist and perfusionists have been given ample time for weaning. Inotropic support is provided, full ventilation ensues, calcium is repleted, and acid-base status is corrected. Some routinely use nitric oxide to assist with reduction of pulmonary vascular resistance.

A separate 4-0 pledgeted polypropylene suture is placed just above the outflow clamp for deairing. The aortic graft is backbled. Volume is left in the heart, and the outflow cap is loosened to help deair the ventricle. The outflow graft is then connected. The bend relief should not be latched until the outflow graft clearly does not kink when being attached to the pump. The patient is weaned off cardiopulmonary bypass or to a flow rate of 1-2 L/min.

The LVAD is started at the lowest setting for revolutions per minute (RPM), with the aortic clamp on to continue deairing. With the aortic vent on, the outflow graft clamp is removed. Often, a small rush of air bubbles is visible on the long-axis TEE view, reflecting air around the clamp. Usually, this rush lasts for less than 5 seconds, and the air is removed with the aortic vent.

LVAD flow is slowly increased while right-side function, pressures, and septal motion are monitored. Often, no flow is recorded, but the patient is still doing well. The temptation to increase RPM quickly so as to get high flow should be resisted. In most centers, it is permissible to leave the operating room without full decompression as long as the patient’s hemodynamic status is suitable. Often, “final” settings on the pump are not made for days after the implant. Protamine is administered and all cannulas removed. Chest and mediastinal tubes are placed.

The final position of the LVAD within the chest, especially without the retractor, should be viewed under TEE. In particular, the inflow cannula should be directed slightly posteriorly toward the mitral valve; TEE is crucial for this step. In addition to confirming cannula location, TEE can identify valvular problems.

A bubble study must be performed with the LVAD on in order to determine whether a patent foramen ovale (PFO) is present. In patients who have heart failure and high left-side pressures, such defects can be difficult to detect until the left side is decompressed. If a PFO is identified, it must be repaired.

Some centers advocate an aggressive policy of leaving the chest open for 1 day to allow stabilization before closure. The authors’ approach is to leave the chest open if there are grounds for concern regarding ongoing bleeding or RV functional decline associated with sternal compression. Leaving the sternum open can be an excellent strategy for marginal patients. In this situation, the authors usually wrap a towel in an antimicrobial incise drape (eg, Ioban; 3M, St Paul, MN) and place it in the cavity, with a large drape covering it and the chest.

For bridge to transplant therapy (BTT), the authors prefer to prepare for reentry that occurs with transplant. Initially, the authors try to space the aortic cannulation site and the outflow graft so as to leave space for recannulation, an aortic cross-clamp, and a cuff of sewable aorta. Some surgeons place vessel loops around the SVC and the inferior vena cava (IVC) to facilitate identification. The authors have done this with some reoperative LVAD cases; however, if possible, they try not to create dissection planes unless it is necessary.

The authors take a piece of spare graft to cover the outflow graft from the edge of the bend relief to the aorta. They then place a piece of 1-mm Gore-Tex (W. L. Gore & Associates, Newark, DE) at the base of the pericardium on the left side, where it joins the diaphragm, and use interrupted sutures to reconstruct the pericardium and isolate the LVAD. It is important to try to separate the left lung from the device; this can be quite traumatic at the time of explant. Other barrier products can also be used to help with transplant reentry.

There are several ways of dealing with the driveline. In general, a long tunnel is desirable. The authors have stopped bringing the velour cuff out of the incision; they believe that healing has actually been better without the cuff. The authors place a deep 0 polyglactin suture and use a 3-0 poliglecaprone suture for the subcuticular skin closure. In addition, they authors use two No. 1 polypropylene sutures to provide traction relief around the exit line. These later sutures are removed about 1 month after being placed.

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Complications

Well-known complications include the following:

  • Bleeding that necessitates reoperation or transfusion
  • Neurologic events (including stroke, both ischemic and hemorrhagic)
  • Infections (both LVAD-related and remote)
  • Arrhythmia
  • Respiratory failure
  • Renal failure
  • Hepatic dysfunction
  • Hemolysis [13]
  • Pump thrombosis [14, 15]
  • Rehospitalization

Certain intraoperative complications associated with LVAD implantation are of particular importance. The foremost of these is RV failure. [16] The authors take an aggressive approach to temporary RVAD support. Rather than leave the patient in the operating suite on high doses of multiple inotropes and vasoconstrictors, the authors are inclined to place a temporary RVAD to allow hemodynamic and coagulopathic stabilization. This pump can usually be removed within 5 days.

Another potentially catastrophic intraoperative complication is related to air embolism. Although some air is to be expected, especially as pumping is initiated, persistent air entrainment should lead to suspicion of apical disruption of the inflow cannula.

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