Postoperative VAD Management: Operating Room to Discharge and Beyond: Surgical and Medical Considerations

Perioperative management

This chapter focuses on the early postoperative care of patients with ventricular assist devices (VADs). Appropriate patient selection and optimal implantation techniques greatly simplify postoperative management. Indeed, some problems created by suboptimal implantation techniques are difficult or impossible to correct, short of a return to the operating room. This chapter commences with a discussion of operative factors that influence the early intensive care unit (ICU) course of a VAD patient, reviews early postoperative challenges in the ICU and their management, and addresses the further hospital course leading up to discharge and considerations of postdischarge management once the patient first returns to the community. We start in the operating theatre.

Considerations in the operating room relevant to subsequent ICU care

Appropriate de-airing of the pump and heart is crucial to a successful outcome. The surgeon carries out the de-airing maneuvers in conjunction with the perfusionist and the anesthesiologist while monitoring the transesophageal echocardiogram. A substantial amount of air can be removed from the patient’s left ventricle (LV) and VAD before completing the final connections of the system (i.e., 1—outflow graft anastomosis to aorta or 2—outflow graft connection to the pump housing). If the final step is to anastomose the outflow graft to the aorta, attaching a sump sucker to the outflow graft and then filling the beating heart with blood pushes blood from the heart through the VAD and into the sump sucker. If the final step is to attach the outflow graft to the pump housing, a vent tube can be attached to the pump outlet thread protector. The surgeon and perfusionist fill the beating heart with blood to push blood and air into the vent line.

While the pump and heart are in this initial phase of de-airing, the lungs should be gently ventilated with the patient in a head-down (Trendelenburg) position with a second venting device aspirating blood from the aortic root. While this initial de-airing occurs, the surgical team can accomplish other tasks, including placement of the percutaneous driveline and positioning of the outflow graft in the desired position (e.g., along the diaphragmatic surface of the pericardium and lateral to the right atrium), with a few sutures to prevent migration.

The final de-airing takes place after the pump connections are complete. It is best for each team to develop their own protocol for de-airing; however, the general plan contains the following features. The process begins by fully reinflating the lungs and setting the ventilator to resume regular respirations. The rhythm of the heart is optimized using pacing and medications as necessary. Ideally, the patient will be in a normal sinus or paced atrial rhythm. The perfusionist then decreases venous return and begins partial cardiopulmonary bypass. When the surgeon feels that there is adequate blood in the LV, the pump is powered up and rotor rotation is started, but with a cross-clamp in place on the outflow graft. Blood and air are aspirated from the outflow graft proximal to the clamp via a venting needle. After completing the initial de-airing, the outflow graft is slowly unclamped while monitoring the LV and ascending aorta for air. The vent in the ascending aorta captures any air that escapes the outflow graft vent. Shaking the heart and forcefully ventilating the lungs dislodge smaller bubbles of air trapped along the walls of the heart and pump. After completing the de-airing sequence with the patient in a head-down position, the maneuvers are repeated with the patient in a supine (flat) position.

Air that enters the cerebral circulation may cause brain injury ranging from confusion to more severe focal and global brain injury (e.g., multiple small regions of stroke). Air entering the ascending aorta and right coronary artery (RCA) may cause—at least transiently—right ventricle (RV) dysfunction, resulting in immediate RV dilation and free wall hypokinesis. At this point, it is prudent to go back on full cardiopulmonary bypass in order to push the air through the right coronary circulation and recover RV function.

As the echocardiographer and surgeon monitor for air, they can also assess native cardiac function and the effects of the VAD on the heart. This includes determining valve function (e.g., assessments for mitral, aortic, and tricuspid valve insufficiency) and the position of the ventricular septum relative to the LV and RV cavities. Another important item to check with echocardiography is the position of the inflow cannula relative to the LV septum and free wall. Ideally, the orifice of the inflow cannula will point posteriorly, directly at the mitral valve orifice. Doppler interrogation of the LV cavity confirms nonturbulent flow directly from the mitral valve into the VAD. The inflow cannula should not be angled toward the intraventricular septum, but rather parallel to the septum to avoid septal suction, turbulent flow, and potential ventricular tachycardia.

As the LV fills and begins to eject blood through the aortic valve, the surgeon increases pump rotor speed (revolutions per minute) to a point where the VAD provides adequate systemic blood flow without pulling the ventricular septum toward the LV. Upon achieving this balance of native ventricular function and pump function, the flow of the cardiopulmonary bypass circuit is decreased and eventually discontinued. At this point, the patient’s cardiac output is a combination of the native LV ejection and left VAD (LVAD) pump flow. If systemic flow is adequate and the other echocardiographic indicators of VAD function are satisfactory (e.g., inflow cannula position, septal position, and absence of air in the heart or aorta), the surgeon removes the cardiopulmonary bypass cannulas as the anesthesiologist administers protamine.

Pharmacological management of circulation early after VAD implantation focuses primarily on RV function. This includes inotropic medications (often milrinone, which simultaneously reduces RV afterload) to stimulate RV contractility, vasopressors to maintain adequate systemic blood pressure required for right coronary artery perfusion, and inhaled pulmonary vasodilators (often inhaled prostanoids as a less expensive alternative to inhaled nitric oxide) to reduce pulmonary vascular resistance without causing V/Q mismatch and resultant hypoxemia or systemic hypotension. If blood pressure is low or the patient has poor renal function, low-dose epinephrine or dobutamine may be used for inotropic support of the RV in place of milrinone. Some centers use both low-dose epinephrine and milrinone for support.

After administering protamine, the surgical team typically turns its attention to obtaining hemostasis. The surgeon must also decide whether to close the chest primarily or leave the sternum unclosed and either packed or treated with a vacuum-assisted wound management device. When the wounds are closed or sealed, the implantation team transports the patient to the ICU. If there is significant RV dysfunction, either due to a marginal RV prior to surgery or an injury to the RV intraoperatively, the surgeon may leave the chest open to assist RV function or implant a temporary right VAD (RVAD) either surgically or percutaneously for initial RV support.