Heart failure affects over 5 million Americans, and nearly 550,000 new cases are diagnosed each year. Ten of every 1,000 patients over 65 will suffer heart failure.1 One of every eight death certificates list heart failure as the cause.1 Alarmingly, 80% of men and 70% of women younger than 65 years old diagnosed with heart failure will die as a result of the condition within 8 years.1 In 2006, over 1 million patients had the diagnosis of heart failure noted as one of their health conditions.1 This large patient population places significant financial strain on the healthcare system. Direct and indirect costs associated with heart failure led to approximately $37.2 billion in costs in 2009.1
Left ventricular assist devices (LVADs) are used to treat patients with end-stage heart failure to improve survival and quality of life. Patients who require heart transplantation but who have a poor predicted survival to transplant can undergo LVAD implantation as a bridge to transplantation (BTT). At the time of transplant, the native heart and LVAD are removed and replaced by the donor organ. There are roughly 2,200 cardiac transplantations performed annually in the United States.2 Many more patients could benefit, but transplantation is limited due to a lack of donor organs.2
An LVAD may also be placed in a patient in cardiogenic shock with the intent to remove it after the shock condition has resolved. This indication is termed bridge-to-recovery (BTR). Patients with either precardiotomy cardiogenic shock (fulminant myocarditis, acute myocardial infarction, etc.) or those in postcardiotomy cardiogenic shock (for example, postcoronary artery bypass graft, postaortic valve replacement) may benefit from LVAD placement until the heart has recovered enough function that support is no longer required.3
Another indication growing in prevalence due to the success shown in the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure Trial is the use of an LVAD as destination therapy (DT).4,5 The DT population typically includes patients with end-stage heart failure and poor predictive survival in their current medical state. These patients are also noneligible for transplantation, usually due to advanced age, significant comorbidities, or psychosocial issues contraindicating transplant. Patients undergo LVAD implantation and live the rest of their lives with the device permanently in place.
Of the many LVADs available today, device selection primarily depends on the indication. For instance, the surgeon or interventionalist may choose a short-term, percutaneous device for a patient thought to be implanted as a BTR. Devices such as the Impella 2.5 (Abiomed, Danvers, Mass.), TandemHeart PTVA (CardiacAssist, Pittsburgh, PA), or the Centrimag (Thoratec, Pleasanton, Calif.) can all be placed through peripheral blood vessels similar to the placement of a central line. This technique does not require a sternotomy for implant or explant and can be performed outside of the OR in emergent situations (see Short-term percutaneous ventricular assist devices (VADs))
Long-term LVADs are traditionally implanted through a median sternotomy with the use of cardiopulmonary bypass (CPB), although newer devices and greater experience have allowed some devices to be placed through a thoracotomy.6 Long-term LVADs, such as the HeartMate II (Thoratec), the HeartMate XVE (Thoratec), and the HVAD (HeartWare International, Inc., Framingham, Mass.) are utilized for patients identified as BTT or DT candidates (see Long-term LVADs).
First-generation LVADs are pulsatile devices that mimic the natural pulse created by the native heart. These devices pump in beats-per-minute with a set stroke volume unique to each device. The device generates a flow, or VAD cardiac output, in L/minute. Newer generation devices provide continuous flow through axial or centrifugal motions. The device dynamics differ because there is no longer a systole and diastole created by the pump. Volume that enters the LVAD is circulated continuously.
There are some differences in patient management depending on whether LVAD flow is pulsatile or continuous. This article focuses on the postoperative management of long-term LVAD patients (both pulsatile- and continuous-flow devices), illustrating key aspects of both inpatient and outpatient management so the NP can provide optimum patient care.
Perhaps the greatest factor affecting postoperative success and survival is the preoperative assessment. The typical LVAD patient should have a New York Heart Association class III-IV or the American College of Cardiology/American Heart Association Stage C-D heart failure symptoms, an ejection fraction less than 25%, significant functional limitation for at least 90 days despite the use of maximal medical therapy, functional limitations with a cardiopulmonary exercise test with a peak oxygen consumption (VO2) value less than 14 mL/kg/minute, or inotrope dependent.7 These factors support the need for a long-term versus a short-term device.
Patient risk factors that need further assessment before LVAD placement are the presence of chronic kidney disease, derangement in coagulation, liver dysfunction, malnutrition, right ventricular (RV) dysfunction, and significant pulmonary dysfunction. Identification of these risk factors will help NPs address potential issues to optimize patient health before surgery. Preoperative optimization will help postoperative recovery.
Postoperative management of the LVAD patient requires an understanding of LVAD function and how it relates to patient care. This includes optimal hemodynamics and how the LVAD may affect hemodynamics, optimizing preload and reducing afterload, assessing end-organ perfusion, and utilizing echocardiography to assess LVAD performance.
The goal of VAD therapy is to improve end-organ perfusion and resolve the shock state, if applicable. LVAD flows should be titrated to obtain optimal hemodynamics for each patient based on traditional measures of cardiac index (CI) and mean arterial pressure (MAP) (see Optimum hemodynamic goals following LVAD implantation).
Preload and afterload
LVAD flow is a function of preload and afterload. An LVAD is dependent on preload and sensitive to afterload. The greater the volume presented to the device, the greater the amount of flow it can generate. Reasons for decreased preload may be due to hypovolemia related to third spacing, bleeding, tamponade, lack of vascular tone, inflow cannula positioning leading to decreased drainage from the left ventricle (LV) into the device, or RV dysfunction.3 By diagnosing and treating the cause of a decrease in preload, the NP will help optimize LVAD performance.
Conversely, if there is increased afterload, the LVAD will not be able to effectively pump against the increased resistance. When there is an increase in systemic vascular resistance (SVR), flow through the LVAD will decrease. Treating increased SVR with afterload reducing agents or weaning vasoconstrictive agents as tolerated will help increase LVAD flow.
An LVAD increases blood flow by assisting the native heart when it is unable to perform the task effectively. Both pulsatile and continuous-flow devices can lead to a decrease in pulmonary capillary wedge pressure (PCWP), increased CI, and help maintain or improve renal and hepatic function.2,8,9
Pulmonary function may be affected by the congestion seen in heart failure patients. Increasing forward flow through the use of an LVAD will help relieve congestion, decrease shortness of breath, and ultimately improve functional capacity.4 Assessment for a patent foramen ovale (PFO) should be performed during LVAD implantation. A PFO may be present in up to 25% of the general population.10 Under normal intracardiac pressures, blood does not cross the PFO due to higher left-sided than right-sided pressures. By unloading the LV with an LVAD, the pressure difference changes, resulting in a decrease in left-sided pressure. This allows deoxygenated blood to cross the PFO and circulate peripherally. Diagnosis can be made intraoperatively with the use of a transesophageal echocardiogram (TEE) and the injection of agitated 0.9% sodium chloride. Bubbles seen in the LV after injection of the normal saline indicate the presence of a PFO and require closure.10 If assessment does not occur in the OR, then presence of a PFO must be in the differential diagnosis when encountering a patient with hypoxia despite adequate LVAD flows and a clear chest radiograph.
Renal dysfunction is common in cardiogenic shock and advanced heart failure patients. Rising renal function studies often indicate poor cardiac perfusion of all organs. Many of these patients require ultrafiltration or aggressive diuresis before LVAD implantation to relieve volume overload. Assessing renal function studies along with urine output post-op will help gauge LVAD performance. By increasing CI with the help of the LVAD, greater renal perfusion should result.9,11 In the initial post-op period, it is not uncommon to see oliguria or anuria in a patient who was in cardiogenic shock preoperatively. By optimizing fluid status and providing a greater preload to the LVAD, organ perfusion will increase leading to normalizing renal function.
Gastrointestinal (GI) issues are present in many patients following cardiac surgery. LVAD patients may experience GI abnormalities due to the presence of the device. Elevated bilirubin levels may be seen following LVAD implant due to hemolysis caused by the device itself. A VAD can create negative pressure, or a vacuum, that is used to fill the device. In the setting of low preload or turbulent blood flow, this vacuum can lead to a shearing of blood vessels creating hemolysis.3 Maintaining adequate preload and ensuring the proper alignment of the inflow cannula at the time of surgery will help reduce the potential for hemolysis. Liver function studies may be elevated preoperatively due to cardiogenic shock or a persistent low-flow state as seen in end-stage heart failure. These levels should begin to normalize shortly after LVAD implantation.9
Continuous flow LVADs may cause arteriovenous (AV) malformations leading to GI bleeding, which could be due to a decrease in pulsatile blood flow. This lack of pulsatility can also lead to an "acquired von Willebrand" condition contributing to GI bleeding. Reducing the pump speed to allow more pulsatility and discontinuing anticoagulation, either temporarily or permanently, has been shown to decrease or eliminate the bleeding.6
Neurologic complications can be the most devastating risk of LVAD therapy. Due to the large surface area of artificial material that the blood contacts, there is a potential for thrombus formation. Anticoagulation can be accomplished using aspirin, warfarin, or other antiplatelet therapies. Patient presentation preoperatively and intra-op management may also affect post-op neurologic status. A low-flow state as experienced in cardiogenic shock can lead to poor cerebral perfusion affecting neurologic status post-op. Rapid diagnosis and treatment of hypoxia or an embolic event can minimize neurologic dysfunction.
Echocardiography has always played an important role in the management of LVAD patients, but with the growing use of continuous-flow devices, its role is expanding. Intraoperative TEE has traditionally been used to assess LVAD cannula placement with pulsatile devices. Echocardiography can also be used to assess for cannula migration and cannula obstruction due to thrombus or positioning against a wall of the heart. The risk of complete unloading of the LV with a pulsatile device is limited due to the VAD diastolic filling phase. With continuous-flow devices, the LVAD is constantly unloading the LV without a diastolic phase. Minimal changes in preload or pump speed can dramatically affect LV dynamics. Because of this, echocardiography is utilized when manipulating device settings.6,12 Some institutions have created protocols to consistently assess LVAD settings using echocardiography in the inpatient and outpatient settings.6
Routine echocardiography should include assessment of RV function, cannula position in the LV, aortic valve opening in continuous-flow devices, the presence of mitral regurgitation, and an estimation of PCWP. This information can assess LVAD effectiveness and become the basis for pump speed changes in continuous-flow devices.
Any cardiac surgical procedure may result in bleeding complications, especially with the use of anticoagulation, RV dysfunction, dysrhythmias, and infection. In the LVAD patient population, the NP will need to understand the significance of these complications in relation to LVAD therapy.
Bleeding and anticoagulation
Bleeding is a potential complication following any surgical procedure, particularly LVAD placement. Most LVADs are implanted with the use of CPB. CPB can contribute to clotting factor dysfunction and depletion leading to an increased risk of bleeding postoperatively. Patients that are hypothermic following surgery are also prone to bleeding. Proper rewarming in the OR and in the ICU will help return a patient to normothermia, reducing the risk of bleeding.
Coagulopathy may also be present in the advanced heart failure patient population. Due to cardiogenic shock or long-term end-stage heart dysfunction, patients may have some level of liver dysfunction leading to a decreased ability to produce the appropriate clotting factors. The NP should assess the need for transfusion of whole blood, fresh frozen plasma, or administration of medications that reverse bleeding, depending on the nature of the coagulopathy.
Bleeding can also lead to cardiac tamponade. Diagnosing tamponade early through hemodynamic changes, low LVAD flows, chest radiograph, or echocardiography can lead to prompt treatment and re-optimization of LVAD function.
One of the best ways to prevent bleeding and tamponade is meticulous surgical care. Taking time to ensure all possible areas of bleeding have been addressed before closing the chest will decrease the possibility of returning to the OR to treat bleeding from surgical sites.
Due to the potential of thrombus formation, the NP should initiate anticoagulation early in the post-op period to prevent a thromboembolic event. Generally, once post-op bleeding has subsided (chest tube output less than 1 mL/kg/hour, normalized coagulation studies), anticoagulation is initiated. This may be in the form of heparin, argatroban in the setting of heparin-induced thrombocytopenia, or warfarin. Activated partial thromboplastin time is maintained between 60 and 80 seconds, with a goal international normalized ratio (INR) of 2 to 2.5. Special consideration should be given to patients who demonstrate the propensity for hypercoagulability. Testing for heparin-induced antibodies, protein C and protein S deficiencies, and antithrombin III deficiencies may help diagnose this condition. If a patient is identified as hypercoagulable, an anticoagulation regimen consisting of heparin, argatroban, aspirin, warfarin, clopidogrel, and/or dipyridamole may need to be initiated sooner than normal.3 Drug combinations vary based on the device used the preference of the surgeon or cardiologist for I.V. anticoagulation, and the particular presentation of the patient.
The goal of anticoagulation is to prevent thrombus formation while avoiding hemorrhage. INR and activated partial thromboplastin time levels should be individualized for each patient, taking into account their anticoagulation history, initial presentation before implantation, and the specific LVAD implanted. New data suggest lowering the goal INR (1.5–2.5) for long-term continuous-flow LVAD patients due to a low rate of thrombus and the risk of hemorrhage.13 The NP should consult with the surgeon and cardiologist to establish an anticoagulation goal.
When supporting only the LV with a VAD, the heart becomes dependent on the RV to function properly enough to provide an adequate preload to the LVAD. Preoperative testing should include evaluation of the RV. Placement of an LVAD leads to the unloading of the LV. Pulling volume rapidly out of the LV into the LVAD can cause a shifting of the interventricular septum. Shifting of the septum can lead to residual RV dysfunction.12 Adjusting either the vacuum the LVAD uses to pull volume from the LV or the speed of a continuous-flow device will help alleviate the septal shift and improve RV function. With continuous-flow devices, LVAD speed adjustments are usually performed with echocardiogram assessment to assure there is no septal shifting with optimal LV unloading.12
In the initial post-op period, a patient may experience fluid shifting or may receive volume in the form of blood or blood products, which leads to an increase in the central venous pressure (CVP). If the RV is not healthy enough to handle this increase in intravascular volume, LVAD flows will begin to suffer. Treatment of RV dysfunction may include initiation of inotropic therapy, such as milrinone or dobutamine, utilization of pulmonary vasodilators to decrease RV afterload, ultrafiltration or hemodialysis to remove excess volume, or, in extreme cases, placement of a right ventricular assist device. In patients with biventricular heart failure, LVAD therapy alone is contraindicated. In the event of bi-ventricular failure, the patient may be eligible for BiVAD support. In this case, an RVAD and an LVAD are used to support both ventricles. Some devices are able to be utilized in either the RVAD or LVAD position while others can only be utilized to support either the RV or LV. If a patient who receives an LVAD-only device and needs additional RV support, a separate RVAD can be used for short-term or long-term support.
A dysrhythmia, such as ventricular tachycardia or atrial fibrillation, may lead to a decrease in LVAD flows, but unlike an intra-aortic balloon pump, an LVAD is not triggered by the heart's native rhythm. This allows the device to continue pumping volume despite the rhythm. Flows may be lower because of the effects the dysrhythmia has on preload. If the unsupported RV is affected by the dysrhythmia and unable to deliver volume effectively to the LVAD, flows will decrease. Diagnosing the dysrhythmia and treating it effectively will ultimately improve LVAD flows. Dysrhythmia treatment may include medications to control the rhythm, pacing to override the dysrhythmia, or electrical cardioversion or defibrillation. When cardioverting or defibrillating a patient on LVAD support, some devices require manipulation prior to delivering a shock. Other devices have been built to withstand these procedures. Follow the LVAD manufacturer's specific instructions for defibrillation or cardioversion for the patient with a LVAD.
Continuous-flow devices can create a suction condition that causes the walls of the LV to collapse when there is little or no volume in the LV. This suction event can be arrhythmogenic. To treat it, the LVAD speed can be decreased and preload can be increased through the administration of fluid.6
Infection is a major cause of morbidity and mortality in the LVAD patient population, so prevention is one of the main goals of long-term therapy.14 Infection can occur at the percutaneous line site, within the pocket created for the LVAD to rest, or within the device itself (VAD endocarditis). Pre-op and post-op antibiotic regimens should be established to prevent infection. Infections starting at the percutaneous site may lead to pocket infections and ultimately device infection. VAD endocarditis is the most serious of these infections and may require the device to be replaced or urgent transplantation.14 Meticulous surgical care during device implantation and attention to the percutaneous line postoperatively are important measures in infection prevention.14
To minimize the risk of infection, all pre-op invasive lines should be removed and replaced with new ones, if necessary. This should be done either immediately post-op if possible, or if infection is suspected. Antibiotic treatment should be initiated in cases of leukocytosis and fever. Wound, blood, urine, and sputum cultures should be obtained to identify the source of infection. Most VAD infections are due to Gram-positive organisms. Gram-negative infections are also commonly seen in VAD therapy and result in a greater risk of mortality when compared to Gram-positive infections. The highest risk of mortality results from fungemia.15 Until the culprit organism is identified, broad-spectrum antibiotic coverage should be implemented. Early endotracheal extubation should be a goal following surgery and will help in preventing infection.
Meticulous wound care around the percutaneous line is also necessary to prevent infection.14 (see ). Hospital personnel, patients, and their families should know sterile techniques for dressing the wound. This process is continued as long as the LVAD is in place. Caution must be taken to avoid manipulation of the percutaneous line, especially once it has begun to heal. Patients must be instructed not to place stress on the line, which will disrupt the skin surrounding the wound, leading to a potential infection. Patients are instructed to use abdominal binders or other stabilization devices to limit accidental manipulation of the line. The NP should teach patients and families to recognize signs and symptoms of infection and to report these findings immediately.
Pulsatile-flow devices are generally larger devices with large percutaneous exit lines. Continuous-flow devices are generally smaller and have a smaller percutaneous line. The smaller line is beneficial for infection prevention.11
Rehabilitation of the LVAD patient requires attention to nutritional state and focuses on increasing activity. The NP should work in collaboration with multiple disciplines to optimize patient health and recovery from surgery.
Cardiac cachexia is often present in advanced heart failure patients with weight loss occurring in as much as 50% of this population.14,16 It may be necessary to administer tube feedings, parenteral infusions, or nutritional supplements to improve patient nutritional status. Enteral feeding is the preferred option.16 Frequent assessment of albumin and prealbumin levels will help direct feedings and supplementation to achieve nutrition goals.
Proper nutrition also plays an important role in wound healing. Initiation of enteral or parenteral feedings in the initial post-op period is essential to optimize nutrition. Due to LVAD placement in a preperitoneal pocket in the left upper quadrant, the device itself may put pressure on the stomach causing the patient to feel full.16 Smaller, more frequent meals are encouraged once the patient is tolerating oral intake.
Patient activity should be increased as soon as tolerated following LVAD implantation. Activity may include range of motion exercises, getting out of bed into a chair, or ambulating with assistance. Physical therapists and occupational therapists are important members of the treatment team. A physical and occupational therapist will work with patients to identify strategies to make transitioning into the home environment easier.
Discharge preparation and outpatient management
Outpatient management of the LVAD patient is evolving as the number of LVAD patients, particularly the DT population, continues to grow. As LVAD therapy becomes more of an accepted treatment option, and as the awareness of its benefits increases in the healthcare community, the number of patients referred for treatment will likely continue to rise.
The VAD NP will establish many important outpatient processes before discharge to ease the transition into outpatient life and independent functioning on LVAD support. Patients and/or family members must be able to demonstrate competency with device management and troubleshooting should an issue arise. The VAD NP educates the patient on the components of the LVAD (batteries, primary console, and monitor) and how to recognize and address any malfunctions in device performance.
The referring physician and/or primary care provider will be notified that the patient has received LVAD therapy. Key points regarding device function and physical exam differences (nonpalpable pulses in continuous-flow device patients) are communicated. Local emergency medical services (EMS) and the local ED are also notified in case the patient presents in an emergency scenario. The key device and physical exam information is also communicated to EMS personnel.
Aside from medical personnel, local utility companies also need notification of an LVAD patient in the community. Because these devices rely on electricity, through either charged batteries or direct connection to an outlet, the patient should be placed on a priority status in the event of a communal disruption in utility services.
During routine clinic visits, the NP may need to adjust the patient's anticoagulant medication or titrate heart failure medications. In continuous-flow LVAD patients, echocardiography plays a key role in the management of their devices. Routine evaluation of LVAD performance via echocardiography allows adjustments to be made to the device to optimize performance and aids in troubleshooting when problems arise.
An evolving treatment option
Long-term LVAD therapy for the advanced heart failure patient population can lead to a significant improvement in patient lifestyle. As this therapy becomes more accepted and recognized, NPs will become involved with LVAD patient care. These patients require lifelong care, not only for the LVAD but for other ailments as well. Understanding the function of the LVAD, how it can affect a physical exam, and key aspects to help the LVAD function optimally will allow NPs to provide quality patient care.
Optimum hemodynamic goals following LVAD implantation
CVP: 10-20 mm Hg
Systolic BP: 100-140 mm Hg (pulsatile-flow devices)
MAP: 60-90 mm Hg (continuous-flow devices)
CI: ≥2.2 L/min/m2
Urine output: >1 mL/kg/hr