13
Surgical Technique for Implantation
Overview
This section describes the surgical considerations necessary to prepare, implant, and explant the CentriMag system. Standard surgical
techniques will be used for implantation of the system. The components of the circuit will be similar for most patients, although the
surgical procedures may vary according to the patient’s anatomy, circumstances of support initiation and hospital protocols. In
general, the procedures are as follows: the cannulas are tunneled and positioned for left, right, or biventricular support. The
extracorpeal circuit (or circuits) is prepared, primed, connected to the cannulas, and subjected to a final inspection of the circuit;
support is then initiated.
If CentriMag cannulas or other centrally-placed cannulas are used, the surgical approach for implantation
will usually include the
following general order of process:
1.
Sternotomy
2.
Tunneling
3.
Cannulation
If the condition and stability of the patient permit, all cannulas should be tunneled and brought through the skin of the anterior
abdominal wall (the subcostal region) prior to cannulation of the heart and major vessels. For left heart LVAD support, the drainage
cannula will be placed in the apex of the left ventricle or left atrium and the return cannula will usually be placed in the ascending
aorta. If ambulation is planned, consideration should be given to placement in the axillary artery. If an RVAD for right heart support
is needed, the drainage cannula will usually be placed in the right atrium and the return cannula will be placed in the proximal
portion of the main pulmonary artery.
CAUTION: The position of the drainage cannula in the left ventricular apex should be positioned pointing toward the
mitral valve (the tip should be placed in the direction of the mitral valve) in order to maximize drainage and minimize
suction events.
CAUTION: The preferred placement of the return cannula is in the ascending aorta. Confirm that the point of
anastomosis is not calcified to avoid the risk of a stroke.
The circuit is primed with a balanced electrolyte solution, deaired, and inspected. Connection of the primed circuit to the cannula
connector is made while adding fluid to the connection to exclude air. The cannulas are secured to the skin with sutures. All
external connections should be further secured with bands for added security and circuit integrity. The pump is positioned on the
motor and the console is powered on and speed set to at least 1000 RPMs with a clamp on the outlet tubing.
CAUTION: If the clamps are removed before the speed is set higher than 1000 RPMs, there is a risk of retrograde flow.
NOTE:
If other manufacturers’ cannulas are used, follow standard surgical techniques applicable to those cannulas.
The status of the heart is monitored with echocardiography, hemodynamic monitoring, palpation, and direct visualization, to ensure
adequate intravascular volume, CPB flow is reduced while VAD support is initiated. After cannulation, the sternum and skin are closed
using standard surgical techniques. If unable to close the sternum due to mediastinal bleeding, or if edema causes compromised
flow, the chest may be packed, sternum splinted open, and the skin opening covered with an appropriate patch for closure later.
Monitoring
Hemodynamic assessment before and during CentriMag system support should include standard cardiac surgery pressure monitoring
such as a central venous catheter, an arterial line, and a pulmonary artery catheter. Before initiating CPB and placement of the
CentriMag
TM
cannulas, transesophageal echocardiogram should be performed to rule out the following:
A patent foramen ovale or other septal defects
Intra-atrial and intra-ventricular thrombus
Aortic valve insufficiency
Valvular dysfunction
Any other structural abnormalities that may interfere with the safe operation of the device (i.e. trabeculae or ruptured chordae)
TEE should be used to visualize the heart chambers and to ensure that the heart is completely deaired prior to initiation of support.
TEE may also be used to assess cannula tip position, ventricular volume, ventricular size, optimal neutral position of the ventricular
septum, and the amount of unloading in the heart chambers.
If CPB is used for the implant, anticoagulation appropriate for CPB must be administered before CPB. If the implant is to be
performed without CPB, heparin should be administered to the patient prior to cannulation with a recommended target of an
activated coagulation time between 200 and 250 seconds.
Tunneling
The cannulas should be tunneled through the chest wall using a standard surgical technique. It is recommended that tunneling be
performed prior to cannulation so that the cannula can be positioned without bends or kinks. Prior to tunneling, cover the tip of the
cannula with the included tunneling cap, or if none is included, a glove tip or other material to prevent debris from entering the
internal lumen. At the end of the case, the cannulas should be securely sutured to both fascia and skin, with minimal tension. For
more information, refer to the instructions for use for the cannulas.
CAUTION: If the cannula kit does not include a tunneling cap, use caution to not tear or damage the glove tip or other
material to prevent damaging the cannula connector.
