Anesthesia for noncardiac surgery in adults with a durable ventricular assist device

INTRODUCTION — Ventricular assist devices (VADs) are a treatment option for patients with advanced heart failure. Patients supported with a VAD may require noncardiac surgery for a variety of indications. (See "Treatment of advanced heart failure with a durable mechanical circulatory support device" and "Management of long-term mechanical circulatory support devices".)

Key considerations for anesthesia for noncardiac surgery in patients with durable VADs are reviewed here. Other topics discussed include the indications, implantation procedures, medical management, and emergency care for patients with a durable mechanical circulatory support (MCS) device:

●(See "Treatment of advanced heart failure with a durable mechanical circulatory support device".)

●(See "Management of long-term mechanical circulatory support devices".)

●(See "Emergency care of adults with mechanical circulatory support devices".)

●(See "Anesthesia for placement of ventricular assist devices".)

GOALS FOR MECHANICAL CIRCULATORY SUPPORT — A VAD performs as a supplemental cardiac pump by taking blood returning to a failing ventricle and ejecting it downstream, either into the ascending aorta in the case of a left ventricular assist device (LVAD), or into the pulmonary artery in the case of a right ventricular assist device (RVAD).

A VAD may be implanted in a patient eligible for cardiac transplantation until a donor organ is available (ie, bridge to transplantation) or in a patient who is not currently eligible for transplantation but may become eligible [1,2]. In some patients, a durable VAD is implanted for permanent ventricular support (ie, destination therapy) [2,3]. (See "Treatment of advanced heart failure with a durable mechanical circulatory support device", section on 'Indications'.)

Temporary percutaneous ventricular assist devices are also available for rapid implantation when mechanical circulatory support is acutely needed for survival (ie, bridge to recovery). Such patients are generally not candidates for noncardiac surgical procedures. (See "Short-term mechanical circulatory assist devices".)

TYPES OF CONTINUOUS-FLOW DEVICES

Device components — Continuous-flow devices unload the failing ventricle through the action of an axial or centrifugal impeller that rotates at high speeds [4-8]. Device components include an impeller pump, connected by a small driveline to a system controller that is typically externalized to the upper abdomen. The system is typically powered by wearable batteries or by an external alternating current power source. These nonpulsatile devices are placed in the thoracic cavity with blood flowing through an inflow cannula in the apex of the left ventricle (LV) to the pump and returning back to the circulation through an outflow cannula in the ascending aorta. Since 2010, all newly implanted VADs have been continuous-flow devices [4,9].

Specific devices — The HeartMate 3 (picture 1) and HeartWare HVAD (figure 1) are the devices most likely to be encountered in a patient presenting for elective or urgent noncardiac surgery [10]. The HeartMate 3 is the only device currently available for implantation [4-8,11,12]. (See "Treatment of advanced heart failure with a durable mechanical circulatory support device", section on 'Specific devices'.)

PREANESTHETIC CONSULTATION — Preoperative discussion with knowledgeable clinicians having training in mechanical circulatory support (eg, a specialized VAD team) is extremely important. This facilitates awareness of potential patient-specific and device-specific problems and avoidance of pitfalls that may arise in the perioperative period, as well as coordination of care in the postoperative period [4,13].

A checklist is helpful to ensure that important and unique perioperative issues for patients with a VAD are comprehensively addressed (table 1).

Device-specific issues — The settings and details that are specific for the implanted device should be documented. These include the type of device, implantation date, pump speed, pump flow, pump power, and pulsatility index (table 2). (See "Management of long-term mechanical circulatory support devices", section on 'Device interrogation' and 'Monitoring VAD parameters' below.)

The location of the externalized driveline on the abdominal wall is also noted, and that site is examined for any sign of infection. Previous history of difficulties with VAD function, any alarms or VAD-related complications (eg, thromboembolism, infection, mucosal bleeding), and adequacy of device function for the individual patient's current clinical status should be noted [4].

Patient-specific issues — Assessment of the patient's preoperative clinical condition includes assessment of the patient’s cardiovascular history, current health, and urgency and extent of the surgery to be performed [14].

Perioperative problems and management issues may include:

●Cardiovascular issues

•Original indication for VAD implantation – Of note, the current left ventricular ejection fraction (LVEF) has much less meaning in the presence of an LVAD [15]. (See "Treatment of advanced heart failure with a durable mechanical circulatory support device".)

•Presence of right heart failure – Right heart failure is often present after implantation of an LVAD [4-8]. Right heart failure may be exacerbated by decreases in LV pressure and size after VAD implantation, leading to interventricular septal bowing and distortion of right ventricular (RV) geometry and mechanics, particularly if the patient had underlying biventricular dysfunction. (See "Management of long-term mechanical circulatory support devices", section on 'Right heart failure'.)

•Presence of a pacemaker and/or implantable cardioverter defibrillator (ICD) – Generally, perioperative considerations regarding pacemakers and ICDs do not differ in VAD-supported patients [13,16,17]. (See "Perioperative management of patients with a pacemaker or implantable cardioverter-defibrillator".)

However, defibrillator pads must be positioned on the chest so that the heart is between the pads. It is important to avoid placement of the pads over critically important devices (eg, pacemaker, ICD, VAD) or a driveline. In some cases, this may necessitate a more lateral pad placement on the left side of the chest or anterior-posterior placement, with a pad placed in the center of the chest and the other in the center of the back. (See "Management of long-term mechanical circulatory support devices", section on 'Ventricular arrhythmias'.)

•Other cardiovascular pathophysiology (eg, aortic insufficiency).

•Current level of physical activity. (See "Management of long-term mechanical circulatory support devices", section on 'Exercise performance'.)

●Pulmonary comorbidities – Examples include pulmonary hypertension, preexisting chronic obstructive pulmonary disease, pneumonia, recent changes in oxygen requirements, or decreased physical activity. (See "Evaluation of perioperative pulmonary risk" and "Strategies to reduce postoperative pulmonary complications in adults".)

●Hematologic abnormalities – These include risk of perioperative thrombosis or, conversely, coagulopathy and risk of bleeding requiring transfusion or need for reversal of anticoagulation. If emergent reversal of anticoagulation is needed for surgery, then it is advisable to seek guidance from the VAD management team or a pharmacist who is specifically knowledgeable in anticoagulation reversal in this setting (see "Management of long-term mechanical circulatory support devices", section on 'Thrombosis' and "Management of long-term mechanical circulatory support devices", section on 'Bleeding'). The patient's anticoagulation regimen and laboratory tests should be reviewed. Thromboembolism remains one of the most serious complications of VAD implantation [7,11,18]. All types of VADs require anticoagulation, usually with heparin or warfarin, which should be noted in the history, and the presence of anemia or coagulopathy is identified on preoperative laboratory tests. (See "Management of long-term mechanical circulatory support devices", section on 'Antithrombotic therapy' and "Management of long-term mechanical circulatory support devices", section on 'Thrombosis' and "Management of long-term mechanical circulatory support devices", section on 'Bleeding'.)

For elective surgery, the level of anticoagulation may be decreased toward the lower limit of the manufacturer's recommendation during the perioperative period or discontinuation of warfarin and beginning of bridging therapy with heparin may be employed. We do not give agents to reverse anticoagulation to VAD-supported patients for most elective surgical procedures [19-21]. Exceptions include neurologic procedures and some ophthalmologic procedures. The anesthesiologist, VAD management team, and surgeon should collaborate to plan anticoagulation safely during the perioperative period, which may include a heparin bridge in selected patients. (See "Perioperative management of patients receiving anticoagulants".)

●Neurologic comorbidity – Examples include abnormal mental status, prior cerebrovascular accident, or embolic stroke. (See "Management of long-term mechanical circulatory support devices", section on 'Stroke'.)

●Renal comorbidity – Examples include renal insufficiency, requirement for dialysis, urinary tract infection.

●Hepatic comorbidity – Examples include liver insufficiency, congestive hepatopathy, coagulopathy. (See "Congestive hepatopathy".)

●Presence of diabetes and difficulties with glycemic control – (See "Perioperative management of blood glucose in adults with diabetes mellitus".)

●Infectious complications (eg, related to VAD implantation) – (See "Management of long-term mechanical circulatory support devices", section on 'Infection'.)

Planning for postoperative care — Planning for the immediate postoperative period includes arrangements for transfer to the most appropriate location to monitor the patient’s recovery from anesthesia and deliver postoperative care. Ideally, recovery is in a monitored environment with telemetry and staff specifically trained in the emergency care of patients with a VAD. In many institutions, personnel in the post-anesthesia care unit (PACU) may be unfamiliar with such patients; thus, recovery from surgery and anesthesia in the intensive care unit (ICU) is often appropriate. (See "Emergency care of adults with mechanical circulatory support devices".)

SELECTION OF ANESTHETIC TECHNIQUE — Patients supported with a VAD receive general anesthesia for most surgical interventions. Due to the need for continuing anticoagulation, neuraxial anesthetic techniques are generally contraindicated in most VAD patients. (See 'Management of hypotension' below.)

However, placement of a peripheral nerve block with ultrasound guidance is relatively safe in patients receiving chronic anticoagulation therapy, and such techniques may be particularly useful for surgical procedures involving upper or lower extremities. Sedation with monitored anesthesia care (MAC) is usually a good choice when feasible (eg, endoscopy procedures).

INTRAOPERATIVE ANESTHETIC MANAGEMENT — Intraoperative management of a patient supported by a VAD includes hemodynamic and VAD monitoring and management, anesthetic management, and support for potential complications such as cardiac arrest. Given the complexity of management of these patients, multidisciplinary involvement and presence of an individual with expertise in managing the VAD is recommended (eg, perfusionist, subspecialized nurse practitioner, cardiac anesthesiologist, cardiologist, cardiac surgeon).

Management of the VAD power source — Patients with an implanted VAD are transported within the hospital to the preoperative holding area, operating room (OR), post-anesthesia care unit (PACU), or intensive care unit (ICU) using battery power for the VAD. Upon arrival to a destination, the VAD should be promptly switched from battery power and connected to the power base unit of the device, which is connected to a wall electrical power outlet. Typically, the battery packs are simultaneously connected to a power source to allow recharging.

In the event that a power base unit is not available, a patient's VAD can remain on battery power for several hours. However, a backup battery should always be available, and it is best to connect the VAD to an external power outlet to obviate the need to monitor battery power.

Intraoperative monitoring

Monitoring VAD parameters — VAD parameters may be monitored on a console or by accessing the patient controller. Continuous-flow VADs provide displays of pump speed (revolutions per minute [RPM]), flow (L/minute), power (watts [W]), and the dimensionless pulsatility index (PI) (table 2) [4,5]. If suboptimal device function is suspected, contact the VAD management team for troubleshooting. (See "Management of long-term mechanical circulatory support devices", section on 'Device interrogation'.)

●Pump speed – Pump speed is measured in rotations per minute (RPM), and adjustments during noncardiac surgery are rarely required.

●Pump flow – Pump flow is measured in liters/minute (L/min) and is mainly determined by the pump speed setting and the pressure gradients across the pump (ie, preload and afterload). Pump flows are calculated from the pump speed and power use, with higher pump speeds and power resulting in higher displayed flows. However, these flows are only estimates and are not measured by a flow sensor [4]. In one study conducted in a HeartMate II VAD at normal flows between 4 and 6 L/min, the displayed flow versus the actual flow measured with an ultrasonic flow probe on the outflow graft varied up to 1 L/min [22]. This is partly due to the varying parallel contribution to total cardiac output produced by the native LV in combination with VAD flow [4].

●Pump power – Pump power is measured in watts (W). Generally, there is a linear relationship between pump power and pump flow. Increases in LV preload and high pump speed settings increase pump flow and increase power consumption. The presence of aortic insufficiency increases power consumption due to higher flow through the VAD. An abrupt increase in power output may indicate pump thrombosis or malfunction.

Reductions in power consumption are typically due to reduced preload with reduced pump speed but may also occur with inflow cannula obstruction.

●Pulsatility index – The PI is a dimensionless measure of the extent of LV ejection and reflected in arterial pressure pulsatility. The pulsatility index is inversely related to the amount of assistance provided by the pump. A low pulsatility index typically indicates either low intravascular volume or minimal native cardiac function, and the LVAD is doing more work by off-loading the LV. If the PI is increasing, the native LV is ejecting more of the volume with the LVAD providing minimal assistance. PI is affected by left ventricular preload, afterload, contractility, heart rate and rhythm, and also VAD pump speed.

Noninvasive blood pressure and pulse oximetry — With continuous-flow VADs, there is often no palpable pulse and minimal arterial pulse pressure; thus, automated noninvasive blood pressure (BP) monitors (eg, oscillometry, Doppler method) do not function in approximately one-half of VAD-supported patients. (See "Management of long-term mechanical circulatory support devices", section on 'Physical examination'.)

If current VAD settings allow some level of pulsatility, and there is optimal intravascular volume, then noninvasive BP and pulse oximetry readings may be adequate to monitor device function throughout the perioperative period. Even a small pulse pressure (eg, 10 to 15 mmHg) typically allows use of standard noninvasive BP and pulse oximetry monitoring, which may be acceptable for minor surgical procedures (eg, colonoscopy, bronchoscopy, transesophageal echocardiography [TEE]). However, we do not intentionally reduce pump flow to increase pulsatility and restore BP or oximetry monitoring because this would heighten the risk of VAD thrombus formation [23,24].

Alternatively, use of a manual BP cuff with a handheld Doppler probe to detect distal blood flow can provide reasonably accurate BP measurements. Although this technique requires more effort and may be somewhat cumbersome, it does work well for relatively short cases. Some clinicians use cerebral oximetry in addition to or as a substitute for conventional pulse oximetry. Cerebral oximetry probes are placed on the patient prior to induction of anesthesia to establish baseline levels of cerebral oxygenation. However, for most cases, use of an intra-arterial catheter is the optimal method to monitor BP, as noted below. (See 'Intra-arterial catheter' below and "Emergency care of adults with mechanical circulatory support devices", section on 'Initial clinical assessment'.)

Intra-arterial catheter — If significant fluid shifts or blood loss are anticipated or if accuracy of either noninvasive BP measurements or pulse oximetry are uncertain, we insert an intra-arterial catheter. (See "Emergency care of adults with mechanical circulatory support devices", section on 'Initial clinical assessment'.)

Placement of an intra-arterial catheter may be difficult using palpation alone due to low arterial pulsatility and is typically performed with ultrasound guidance. As noted above (see 'Noninvasive blood pressure and pulse oximetry' above), we do not alter pump flow to achieve greater arterial pulsatility or vessel palpability during placement of an intra-arterial catheter. (See "Intra-arterial catheterization for invasive monitoring: Indications, insertion techniques, and interpretation", section on 'Use of ultrasound guidance'.)

There are no studies to guide this approach; our approach is based on our experience and the known limitations of noninvasive blood pressure measurement and pulse oximetry in patients with a continuous-flow LVAD [20,21,25]. For example, in one study that included critically ill patients, an oscillatory blood pressure could not be obtained in approximately one-third of patients with an LVAD [25].

Transesophageal echocardiography — Availability of equipment and personnel to use TEE is useful in major surgical procedures and serves as a partial substitute for pulmonary artery catheter (PAC) monitoring in selected patients. (See 'Central venous or pulmonary artery catheter' below.)

TEE is also valuable to evaluate the following conditions, particularly in unstable patients:

●Intravascular volume status – (see 'Fluid and hemodynamic management' below)

●Right ventricular (RV) function

●Aortic valve opening

●Aortic valve regurgitation

●Interventricular septal shifts

●Correct position of the VAD cannulae

In the event of severe hypotension or cardiac arrest, TEE is employed to rapidly determine the most likely cause. (See 'Management of hypotension' below and 'Management of cardiac arrest' below and "Emergency care of adults with mechanical circulatory support devices", section on 'Echocardiogram'.)

Central venous or pulmonary artery catheter — In patients with a continuous-flow LVAD and history of pulmonary hypertension or moderate to severe right heart dysfunction who will undergo surgical procedures with a high risk of large fluid shifts or blood loss, we use a central venous catheter (CVC) or pulmonary arterial catheter (PAC). These monitors can provide useful information to guide intraoperative fluid management and assess right heart function.

In patients with mild right heart dysfunction or pulmonary hypertension, a CVC may be sufficient for monitoring, while patients with moderate to severe pulmonary hypertension or right heart failure may benefit from a PAC. If rapid fluid administration or vasoactive drugs are required, either a CVC or a PAC provide sufficient intravenous access. (See "Anesthesia for noncardiac surgery in patients with pulmonary hypertension or right heart failure", section on 'Monitoring'.)

There are no high-quality studies to inform the selection of central venous or PAC monitoring in this group of patients.

Positioning considerations — Hemodynamic effects of surgical positioning may impact VAD function. Placement of the patient in lateral decubitus with one-lung ventilation may result in hypoxia and/or hypercarbia due to shunting of blood through the nonventilated lung, thereby increasing pulmonary vascular resistance (PVR), limiting preload to the VAD, and potentially leading to acute RV failure.

Reverse Trendelenburg position decreases venous return to the heart, whereas Trendelenburg position increases venous return. These effects should be anticipated and managed since maintenance of a consistent and adequate preload volume is important to maintain appropriate VAD output [26]. (See 'Fluid and hemodynamic management' below.)

For patients supported by the total artificial heart with external lines connected to a pulsatile air pump, care must be taken to avoid compression of these conduits during patient positioning. (See "Treatment of advanced heart failure with a durable mechanical circulatory support device", section on 'Types of durable MCS devices'.)

Induction and maintenance of general anesthesia — The decision to perform endotracheal intubation or use a supraglottic airway in a VAD-supported patient is based on the usual criteria for airway management, as well as the type of VAD. Many LVAD-supported patients develop telangiectasias on mucosal surfaces, with epistaxis being a frequent complication. Thus, care should be taken to avoid significant trauma during tracheal intubation or other airway interventions. (See "Airway management for induction of general anesthesia".)

Continuous flow VADs are relatively small and have an intrathoracic location. Consequently, impaired gastric emptying would not be anticipated, and general anesthesia may be conducted without rapid sequence induction.

Considerations for selection and dosing of agents for induction and maintenance of general anesthesia include the degree of dysfunction of the unassisted RV, as well as effects of each agent on major organs previously compromised by severe circulatory insufficiency necessitating placement of a VAD (eg, brain, kidneys, liver). (See "General anesthesia: Intravenous induction agents" and "Maintenance of general anesthesia: Overview".)

Fluid and hemodynamic management — Maintenance of hemodynamic stability in a patient with an LVAD depends on providing adequate preload, maintaining afterload, maintaining adequate heart rate and rhythm, adjusting pump speed as needed, and preventing any hemodynamic changes that would compromise RV function [4]. These are the main determinates of flow through the pump (ie, the pressure gradient across the pump) and total pump output.

Generally, a reasonable target for intraoperative mean arterial pressure (MAP) is within approximately 10 percent of the usual MAP that has been maintained since insertion of the continuous flow VAD, but no lower than 70 to 80 mmHg.

Strategies to maintain hemodynamic stability — Specific strategies to maintain optimal hemodynamic values include the following (table 3):

●Maintain intravascular volume status – Maintenance of intravascular volume status is necessary to provide adequate preload for optimal VAD function. A VAD will only pump the volume delivered to it [26]. Thus, factors that decrease preload will decrease pump flow and existing LV output. Such factors include anesthetic agents, dehydration, hemorrhage, and lateral decubitus and reverse Trendelenburg position.

Also, high intrathoracic pressures due to excessively large tidal volumes or high intra-abdominal pressures (eg, due to CO₂ insufflation during laparoscopy) may decrease venous return, thereby decreasing volume delivered to the VAD [26].

When VAD flow exceeds the available LV preload, the walls of the LV near the inflow conduit can collapse to create a suction event that limits VAD inflow. Although the VAD may temporarily decrease its speed to compensate for decreased preload in these circumstances, such a suction event may precipitate ventricular arrhythmias or hemodynamic deterioration [27-29]. (See "Emergency care of adults with mechanical circulatory support devices", section on 'Echocardiogram'.)

On the other hand, overaggressive fluid resuscitation is also avoided since this may cause RV distention and worsen RV function [4].

●Maintain optimal afterload – VAD flow is sensitive to changes in afterload [4]. Increases in afterload (eg, systemic arterial hypertension) will decrease pump flow and reduce VAD output. Severely increased afterload may lead to stasis within the VAD and acutely increase risk of thrombus formation, particularly if anticoagulation is inadequate during the perioperative period. Thus, appropriate depth of anesthesia should be achieved prior to noxious stimuli such as laryngoscopy or skin incision, and adequate analgesia should be ensured during and after the procedure.

Hypotension should also be avoided. In the setting of euvolemia, we suggest a MAP goal of 70 to 80 mmHg, similar to goals for other surgical patients (see "Hemodynamic management during anesthesia in adults", section on 'Blood pressure targets'). Phenylephrine, norepinephrine, and/or vasopressin are commonly used to treat hypotension during induction or during surgery (table 4) [8]. (See 'Management of hypotension' below.)

There are limited data to suggest that significant or prolonged hypotension may injure perfusion-dependent end-organs [4]. In one retrospective study, MAP <70 mmHg for greater than 20 minutes was associated with acute kidney injury in patients with a nonpulsatile VAD [30].

●Maintain adequate heart rate and rhythm – Arrhythmias causing clinically significant tachycardia or bradycardia can cause malperfusion or hypotension. Management of arrhythmias in these patients is similar to that for patients without a VAD. (See "Arrhythmias during anesthesia".)

●Maintain RV function – Adequate RV function must be assured by minimizing PVR since output from the RV determines the volume ultimately ejected by a left-sided VAD [18]. Thus, increases in PVR due to hypoxemia, hypercarbia, pain, alpha-agonist vasopressors, hypothermia, and/or acidosis should be avoided.

RV dysfunction is most directly diagnosed using TEE. If increasing CVP and/or hypotension with increasing vasopressor requirements are present, as well as low PI, flow, or power on the VAD monitor, then RV failure should be suspected and further investigated with TEE. Treatment may require inotropic support (eg, milrinone, epinephrine) in addition to vasopressor agents to treat hypotension. In some cases, pulmonary vasodilator therapy may be necessary. (See "Anesthesia for noncardiac surgery in patients with pulmonary hypertension or right heart failure", section on 'Hemodynamic management'.)

●Consult with VAD expert regarding pump speed adjustments – Blood flow through the VAD is proportional to the pump speed, with higher RPMs generating more flow [4]. For patients at risk for significant fluid shifts or who are hypotensive, we recommend consultation with a clinician with VAD expertise (eg, perfusionist, subspecialized nurse practitioner, cardiac anesthesiologist, cardiologist, cardiac surgeon) to determine whether VAD pump speed should be adjusted. If hypotension occurs and is not attributable to decreased preload or afterload, but rather to low pump speed or RV dysfunction, then increasing pump speed may be corrective [5]. However, if there is significant RV dysfunction, inotropic support of the RV may be required. (See 'Monitoring VAD parameters' above.)

Increased pump speed with diminished pulsatility has been implicated in causing aortic valve thrombosis, particularly in the setting of interrupted or reduced anticoagulation (eg, the perioperative setting). However, this typically does not occur in the brief time period required to accomplish a surgical intervention. Also, as noted above, when VAD flow exceeds available preload, inflow suction may cause LV wall collapse.

Management of hypotension — Hemodynamic and VAD parameters help to determine management in the hypotensive patient (algorithm 1) (see 'Monitoring VAD parameters' above and "Emergency care of adults with mechanical circulatory support devices", section on 'Approach to hypotension in the conscious patient'):

●If low pump flow is noted on the VAD monitor, this is typically due to low preload. If the patient has ongoing volume loss or unexplained hypotension, initial treatment is volume administration. (See 'Monitoring VAD parameters' above.)

Other causes of low pump flow include RV failure, inflow or outflow cannula obstruction or thrombosis, or rare causes such as cardiac tamponade or pneumothorax. TEE examination is the most effective means to determine the cause. (See "Emergency care of adults with mechanical circulatory support devices", section on 'Low flow' and "Emergency care of adults with mechanical circulatory support devices", section on 'Approach to hypotension in the conscious patient'.)

●If high pump flow is noted on the VAD monitor, check the power reading (see "Emergency care of adults with mechanical circulatory support devices", section on 'High flow'):

•If power is normal, high flow may indicate a low systemic vascular resistance (SVR). If there are other signs of low SVR such as arterial hypotension, a vasopressor should be administered to increase vascular tone (afterload) and maintain MAP at 70 to 80 mmHg. Patients with end-stage heart disease requiring VAD insertion may have resistant hypotension due to preoperative use of angiotensin-converting enzyme inhibitors, heparin, or calcium channel blockers; thus, phenylephrine, norepinephrine and/or vasopressin are typically selected for first-line vasopressor therapy (table 4) [8]. (See "Intraoperative use of vasoactive agents", section on 'Vasopressor and positive inotropic agents'.)

•A sudden increase in power may indicate device thrombosis or malfunction and should prompt an evaluation for the cause (eg, TEE, invasive hemodynamic assessment). (See "Emergency care of adults with mechanical circulatory support devices", section on 'Echocardiographic ramp test' and "Emergency care of adults with mechanical circulatory support devices", section on 'Approach to hypotension in the conscious patient'.)

Management of cardiac arrest — Recognition of intraoperative cardiac arrest may be difficult or challenging in patients with a continuous flow VAD who are sedated or anesthetized, particularly if there is no intra-arterial catheter for BP monitoring. Similar to patients without a VAD, the first step in managing suspected cardiac arrest is to ensure adequacy of the airway and breathing (algorithm 2). Insertion of an intra-arterial catheter is necessary to establish accurate BP readings and obtain ABGs. Defibrillator pads are positioned on an area of the chest that is not directly over the VAD device or driveline (either bilaterally on the sides of the chest or anterior-posterior placement in the center of the chest and on the back). Further management is discussed in separate topics. (See "Emergency care of adults with mechanical circulatory support devices", section on 'Approach to the unconscious patient' and "Management of long-term mechanical circulatory support devices", section on 'Technical problems and device failure'.)

Emergence and extubation — After emergence from anesthesia, extubation criteria are the same as in patients without a VAD (see "Extubation following anesthesia"). Prolonged tracheal intubation and mechanical ventilation should be avoided if possible, to decrease the risk of respiratory infection.

POSTOPERATIVE MANAGEMENT — Postoperative management should be conducted in a fully monitored setting. Noninvasive and invasive monitoring (if present) are continued until major bleeding, fluid shifts, and severe pain have been managed, and all implanted devices have been checked (eg, the VAD itself and pacemaker or implanted cardioverter-defibrillator [ICD]).

●Management of the VAD power source – After transport from the operating room and upon arrival to the post-anesthesia care unit (PACU) or other monitored care setting, such as the intensive care unit (ICU), the VAD is promptly connected to an external power outlet and the battery packs are simultaneously connected to allow recharging. (See 'Management of the VAD power source' above.)

●Maintenance of hemodynamic stability – Similar to the intraoperative period, hemodynamic stability in the postoperative period is maintained by providing adequate preload, maintaining afterload, adjusting pump speed as needed, ensuring an adequate heart rate and rhythm, and preventing any hemodynamic changes that would compromise function of the right ventricle (RV) [4]. (See 'Fluid and hemodynamic management' above.)

●Pain management – The goals of pain management are to achieve adequate analgesia while maintaining hemodynamic stability. Hypertension associated with pain should be avoided since this may increase afterload and decrease pump output. However, over-sedation with opioids or other sedative-analgesics must also be avoided, since this may lead to hypercarbia, hypoxia, increased pulmonary vascular resistance (PVR), and RV dysfunction.

●Pacemaker/ICD management – Reinstitution of prior pacemaker or ICD settings should be assured shortly after the patient's arrival in the PACU, ICU, or other monitored care setting. Since maintenance of adequate rhythm and rate is necessary for proper VAD function, patients with a pacemaker or ICD should have the device interrogated by the electrophysiology team and reprogrammed if necessary. (See "Perioperative management of patients with a pacemaker or implantable cardioverter-defibrillator", section on 'Postoperative management'.)

●Resumption of anticoagulation – Patients supported by a VAD require anticoagulant and antiplatelet therapy to reduce the risk of thrombotic complications such as device thrombosis and embolic stroke. These agents are resumed when feasible (depending on the type of surgery and amount of postoperative bleeding). (See "Management of long-term mechanical circulatory support devices", section on 'Antithrombotic therapy'.)

SUMMARY AND RECOMMENDATIONS

●Goals for mechanical circulatory support – A long-term ventricular assist device (VAD) may be implanted to support a chronically failing ventricle as a strategy either to bridge to transplant, to achieve substantial improvement in end-organ function (ie, bridge to candidacy), or for permanent ventricular support (ie, destination therapy).

●Types of continuous flow devices – Most VADs are miniaturized continuous-flow devices that work by unloading the failing ventricle through the action of an axial or centrifugal impeller rotating at very high speeds. (See 'Goals for mechanical circulatory support' above.)

●Preanesthetic consultation – A checklist is helpful to ensure that important and unique perioperative issues for patients with a VAD are comprehensively addressed (table 1).

•Device-specific issues – Device-specific issues that require assessment include the type of device (figure 2 and figure 1 and picture 1), implantation date, VAD parameters, and location of the externalized driveline on the abdominal wall. In addition, adequacy of device function for the individual patient's current clinical status, prior difficulty with VAD function, and VAD-related complications are noted. (See 'Device-specific issues' above.)

•Patient-specific issues – The extent of end-organ impairment, the presence of post-implantation complications, and the current surgical problem should be noted. Hematologic abnormalities (eg, history of thromboembolism or coagulopathy, chronic administration of anticoagulants, anemia), right ventricular (RV) dysfunction, presence of a pacemaker and/or implantable cardioverter defibrillator (ICD), or pulmonary, neurologic, renal, hepatic, or infectious comorbidities are often present. (See 'Patient-specific issues' above.)

●Selection of anesthetic technique – General anesthesia is necessary for most surgical interventions. However, sedation with monitored anesthesia care (MAC) or placement of a peripheral nerve block with ultrasound guidance are good choices for selected procedures. Due to the need for anticoagulation, neuraxial anesthetic techniques are contraindicated in most VAD patients. (See 'Selection of anesthetic technique' above.)

●Intraoperative management

•Management of power source – VAD patients are transported within the hospital with the device functioning on battery power. When the patient arrives at their hospital destination, the VAD should be connected to a power base unit that plugs into a standard wall electrical power outlet and simultaneously recharges the device batteries. (See 'Management of the VAD power source' above.)

•Monitoring – Intraoperative monitoring for VAD patients includes (see 'Intraoperative monitoring' above):

-VAD parameters (table 2). (See 'Monitoring VAD parameters' above.)

-With continuous-flow devices, there is often no palpable pulse and minimal pulse pressure. Thus, automated noninvasive blood pressure (BP) monitors (eg, oscillometry, Doppler method) and pulse oximeters may not be functional unless a small pulse pressure (eg, 10 to 15 mmHg) is present. (See 'Noninvasive blood pressure and pulse oximetry' above.)

-If significant fluid shifts or blood loss are anticipated or if accuracy of either noninvasive BP measurements or pulse oximetry are uncertain, we insert an intra-arterial catheter.

-Transesophageal echocardiography (TEE) is valuable, particularly in unstable patients, to evaluate intravascular volume status, position of the VAD cannulae, aortic valve opening, aortic insufficiency, or interventricular septal shift. (See 'Transesophageal echocardiography' above.)

-In patients with a continuous-flow LVAD and history of pulmonary hypertension or moderate to severe right heart dysfunction who will undergo surgical procedures that have a high risk of large fluid shifts or blood loss, we use a central venous catheter (CVC) or pulmonary arterial catheter (PAC). (See 'Central venous or pulmonary artery catheter' above.)

•Fluid and hemodynamic management – Maintenance of hemodynamic stability depends on providing adequate preload, maintaining afterload, ensuring adequate heart rate and rhythm, adjusting pump speed as needed, and preventing any hemodynamic changes that compromise device function (table 3). Management of a hypotensive patient depends on hemodynamic and VAD parameters (algorithm 1). (See 'Fluid and hemodynamic management' above.)

•Cardiac arrest – Management of suspected cardiac arrest is described in the algorithm (algorithm 2).

●Postoperative management – Immediate postoperative considerations include maintaining adequate intravascular volume status and optimal hemodynamics, reinstitution of prior pacemaker or implantable cardioverter-defibrillator settings and achieving adequate analgesia. (See 'Postoperative management' above.)