Heart failure is a global health problem with a US and worldwide prevalence of 5.8 million and 23 million, respectively.1
The annual number of reported heart transplant procedures worldwide peaked at nearly 5,000 in 1993 and declined steadily until 2004. More recently, the annual number of heart transplants seems to be increasing slightly. However, the demand for donor hearts greatly exceeds the supply.2
Given that heart transplantation is available to relatively few patients due to the shortage of suitable organ donors, it is not surprising that the need for mechanical circulatory support (MCS) is increasing.
Heart failure results in low cardiac output (CO) and leads to inadequate blood pressure and subsequent reduced blood flow to vital organs including the brain, kidneys, heart, and lungs.
Mechanical circulatory support (MCS) consists of the implantation of a pump to supplement or replace the blood flow generated by the native heart.
MCS can be used to provide temporary or long-term (durable) support. This chapter will focus on pumps that are used to provide long-term support, particularly left ventricular assist devices (LVADs).
The LVAD is a pump that supplements or replaces the function of the damaged left ventricle. LVADs are increasingly used for mechanical support for patients with severe systolic heart failure (HF).
Purpose of LVAD support:
Long-term (durable) LVADs can be implanted as a bridge to transplantation (BTT) or destination therapy (DT).
Long-term LVADs have also been implanted as bridge to recovery of the native heart, but this use is not currently recognized as a treatment option by the Food and Drug Administration (FDA) or the Centers for Medicare and Medicaid (CMS).
BTT: LVADs are implanted in listed patients when it is determined that they may not survive until a suitable donor is identified.
While patients are on the heart transplant waiting list, the LVAD:
Preserves end-organ function by maintaining perfusion
Minimizes the risk of clinical deterioration from heart failure, which might adversely affect their transplant candidacy
Reduces their risk of death
Recent International Society for Heart Transplantation Registry data indicate that in 2012:
DT: LVADs have also effectively supported patients who are ineligible for transplantation.4
CMS guidelines for patient selection for DT include patients who are not transplant candidates and meet the following conditions:
Failed optimal medical management for at least 45 of the last 60 days, are intra-aortic balloon pump (IABP) dependent for 7 days, or are continuously inotrope dependent for 14 days
Left ventricular ejection fraction (LVEF) <25%
Peak oxygen consumption (VO2 max) < or = 14 mL/kg/min (unless patient is dependent on an IABP or inotropes or is physically unable to perform this test)
New York Heart Association (NYHA) functional class IV5
MCS as DT represents a major proportion of all implants in the United States6:
The proportion of implants for DT increased from 14% in 2006-2007 to 41.6% in 2011-2013.
Conversely, the proportion of patients on the heart transplant waiting list at time of implantation decreased from 42.4% (2006-2007) to 21.7% (2011-2013).
Pulsatile: these pumps generate a pulse of blood similar to native cardiac function (Thoratec paracorporeal ventricular assist device, Berlin Heart, SynCardia Total Artificial Heart [TAH]).
Continuous flow: these pumps deliver blood as a continuous jet of laminar blood flow. Both axial and centrifugal flow pumps are classified as “continuous” (HeartMate II, HeartWare).
It should be noted that some of the new continuous flow pumps have a slightly pulsatile feature (not enough to generate a palpable pulse but may provide better washing of the pump and left ventricle).
Short-term devices: those devices that can be used to support a patient for a few hours to days, such as
Continuous flow devices that can be used for right- or left-sided support such as Tandemheart, Impella, or CentriMag
Extracorporeal membrane oxygenation (ECMO), which provides
Support for both right- and left-sided cardiac function and oxygenation (venoarterial)
Pulmonary support alone (venovenous)
Long-term or durable devices: those that can be used to support a patient for years and enable the patient to be discharged to home while on support.
These types of devices can be used as either BTT or DT
Currently approved continuous flow devices include the HeartMate II (axial flow) or HeartWare HVAD (centrifugal flow)6
Future preference may favor continuous flow with a slight pulsatile component. Pulsatility, smaller components, and implantable controllers with transcutaneous energy transfer (which eliminates the need for a percutaneous driveline) are all in clinical trials or development at this time.
Internal (intracorporeal) versus external (paracorporeal) positioning
An LVAD supports the left ventricle.
LVADs are the most common type of devices used for long-term support.
Long-term support: HeartMate II, HeartWare HVAD, Thoratec paracorporeal ventricular assist device, or Berlin Heart
Short-term support: IABP, Impella, Tandem Heart, CentriMag, Maquet, or Medtronic VADs
A right ventricular assist device (RVAD) supports the right ventricle; examples include the
HeartWare HVAD (off-label use)
Thoratec paracorporeal ventricular assist device
A biventricular assist device (BiVAD) supports both ventricles; examples include
Thoratec paracorporeal ventricular assist device
Short-term support devices:
Total artificial heart (TAH): both ventricles are removed and replaced with the device.
Example: SynCardia TAH with freedom driver, which allows for discharge to home as BTT patients.
See Figure 10-1: HeartMate II
See Figure 10-2: HeartWare HVAD
Decreasing myocardial workload through reduction of left ventricular preload and myocardial oxygen consumption
Augmenting systemic circulation maintaining adequate and consistent cardiac output (CO), which in turn improves organ perfusion
Decreasing venous pressure
Unloading the right ventricle
Augmenting pulmonary circulation
Improving preload to left ventricle
This team typically includes interdisciplinary clinicians from the following services: cardiology, cardiovascular surgery, MCS coordinators, heart transplant coordinators, social service, nutrition, and palliative care, and optimally includes representatives from physical therapy, rehabilitation services, the finance department, pharmacy, infectious disease, endocrinology, and others involved in the care of these complex patients.7
Clinical parameters (ability to meet eligibility criteria for cardiac transplantation or CMS guidelines for coverage noted above).
International Society for Heart and Lung Transplantation (ISHLT) Guidelines for mechanical circulatory support (Table 10-1)8:
Cardiac risk scores such as the ones listed below may be used to assist the team with selection and presenting patients with possibly a more accurate assessment of their survival and outcome should they proceed with LVAD:
Seattle Heart Failure Score10,11: estimates mean life expectancy at 1, 2, and 5 years. The score is derived from the following variables:
Continuous variables: age, LVEF, New York Heart Association class, blood pressure, weight-adjusted diuretic dose, lymphocyte count, hemoglobin, serum sodium, total cholesterol, uric acid
Categorical variables: sex, ischemic cardiomyopathy, QRS interval >120 ms, implantable cardioverter defibrillator (ICD)/cardiac
resynchronization therapy, and use of certain medications (β-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, potassium-sparing diuretics, statins, and allopurinol)
TABLE 10-1 International Society for Heart and Lung Transplantation Guidelines for Mechanical Circulatory Support (MCS): Recommendations for Evaluation, Clinical Classification, and Risk Stratification
Level of Evidence
Assess patient for any reversible causes of heart failure.
Assess patient for potential transplant candidacy.
Assess patient’s New York Heart Association functional class.
Determine patient’s Interagency Registry for Mechanically Assisted Support profile.
Long-term MCS for patients in acute cardiogenic shock: reserve for patients:
With ventricular function that is unrecoverable or unlikely to recover without long-term MCS
Who are so ill that they cannot:
– Maintain normal hemodynamics and organ function with temporary MCS.
– Be weaned from temporary mechanical circulatory device or inotropic support.
Who have the capacity for recovery of end-organ function and quality of life:
Without irreversible end-organ damage
Patients who are dependent on inotropic support: consider for MCS due to high mortality associated with medical management.
Patients with end-stage systolic failure who are not in two previous risk stratification categories: monitor at regular intervals to reassess:
Level of risk
Need for MCS
Potential timing of MCS
Patients at high risk for 1-year mortality: refer for advanced therapy such as:
MCS as bridge to transplantation
MCS as destination therapy
From Feldman D, Pamboukian SV, Teuteberg JJ, et al. The 2013 International Society for Heart and Lung Transplantation Guidelines for mechanical circulatory support: executive summary. J Heart Lung Transplant. 2013;32(2):157-187.
Heart Failure Survival Score: used to predict death, urgent heart transplantation (UNOS status 1), and ventricular assist device (VAD) implantation. The score is derived from the following variables11,12:
Continuous variables: LVEF, resting heart rate (HR), mean blood pressure, peak oxygen consumption, and serum sodium
Categorical variables: ischemic cardiomyopathy and QRS interval > 120 ms
TABLE 10-2 International Society for Heart and Lung Transplantation Classes of Recommendations and Levels of Evidence
Level of Evidence
Evidence and/or general agreement that a given treatment or procedure is beneficial, useful, and effective
Data derived from multiple randomized clinical trials or meta-analyses
Conflicting evidence and/or divergence of opinion about the usefulness or efficacy of the treatment or procedure
Data derived from a single randomized clinical trial or large nonrandomized studies
Weight of evidence or opinion is in favor of usefulness or efficacy.
Consensus of opinion of the experts and/or small studies, retrospective studies, registries
Usefulness/efficacy is less well established by evidence/opinion.
Evidence or general agreement that the treatment or procedure is not useful or effective and in some cases may be harmful.
From International Society for Heart and Lung Transplantation Standards and Guidelines Document Development Protocol. Available at www.ishlt.org/ContentDocuments/ISHLT_Standards_and_Guidelines_Development_Protocol.pdf. Accessed June 27, 2015.
A psychosocial assessment (e.g., with the Stanford Integrated Psychosocial Assessment for Transplant [SIPAT] tool).13
It should be noted that individual centers use, score, and weigh these tools differently.
The Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) trial14
The Heart Mate II Trial15
Patient’s and family’s goals and expectations
Progression of heart failure if LVAD is not implanted
Risk/benefits of MCS implantation
Impact (if any) on patient’s eligibility for heart transplantation
Transplant status post implant (if applicable)
Potential perioperative and postoperative complications; impact of complications on potential eligibility for heart transplantation
Survival rate post implant
TABLE 10-3 International Society for Heart and Lung Transplantation Guidelines for Mechanical Circulatory Support (MCS): Contraindications and Recommendations
Level of Evidence
Absolute in setting of:
Acute valvular infectious endocarditis with active bacteremia
Active infection of an implantable cardioverter defibrillator or pacemaker with bacteremia
Patient’s inability to:
Operate the pump and/or respond to device alarms
Notify the MCS team of signs or symptoms of device malfunction or other health care problems
Unsafe living environment for patient
Demonstrated nonadherence with medical recommendations on several occasions
Active substance abuse (including alcohol)
Relative in setting of:
Diabetes-related proliferative retinopathy, or severe nephropathy, vasculopathy, or peripheral neuropathy
Very poor glycemic control
Peripheral vascular disease (depends on extent and severity)
Lack of sufficient social support
Limited coping skills
Significant caregiver burden or lack of any caregiver
MCS not recommended in setting of:
Irreversible multiorgan failure
Neuromuscular disease that severely compromises the patient’s ability to use and care for the device, ambulate, and exercise
Active malignancy with a life expectancy of <2 y
Active psychiatric illness that impairs a patient’s ability to care for the device or that requires long-term institutionalization.
Patients with confirmed cirrhosis or increased Model for End-Stage Liver Disease score are poor candidates for MCS.
From Feldman D, Pamboukian SV, Teuteberg JJ, et al. The 2013 International Society for Heart and Lung Transplantation Guidelines for mechanical circulatory support: executive summary. J Heart Lung Transplant. 2013;32(2):157-187; International Society for Heart and Lung Transplantation Standards and Guidelines Document Development Protocol. Available at www.ishlt.org/ContentDocuments/ISHLT_Standards_and_Guidelines_Development_Protocol.pdf. Accessed June 27, 2015.
Necessary social support, including caregiver responsibilities and burden
Postoperative recovery, including pain management
Medications while MCS is in place
Long-term care implications
Potential for survival following serious complications
Endpoints for and alternatives to MCS therapy
Insurance coverage and financial impact to the patient and family
Impact of noncompliance
Impact on Quality of Life, including limits imposed by the LVAD (such as no underwater activities)
Providing emotional support for the patient and family
Documenting patient’s and family’s goals for implant
Developing a plan for potential complications
Advance care planning regarding end-of-life care and withdrawal of VAD support in alignment with the patient’s advance directives
TABLE 10-4 Triphase Model for Ventricular Assist Device Patient/Family Education and Informed Consent Process
A recent review of these materials indicated that many of these materials were suboptimal because they frequently21:
Were biased toward proceeding with LVAD implantation
Emphasized the benefits of LVADs but provided limited information on the risks, operative procedure, postimplant lifestyle, instructions for caregivers, or alternative therapies (e.g., palliative care)
Cited outdated statistics
Failed to explain the difference between DT and BTT
Had a reading comprehension level > the eighth grade
Failed to meet International Patient Decision Aid Standards
Clinicians should caution patients and family members about these shortcomings and encourage them to discuss their questions/concerns with members of the interdisciplinary MCS team.
Assess and monitor renal function.
Patients with renal dysfunction, volume overload, and/or poor output:
Optimize hemodynamic status (consider inotropic support).
Aggressive diuresis or mechanical volume removal.
Following optimization of hemodynamic status, assess and monitor:
Blood urea nitrogen
24-hour urine for creatinine clearance and protein
Screen for cirrhosis with ultrasound of the liver in the setting of:
History of liver disease
Abnormal liver function tests
Chronic right heart failure
Radiologic and tissue confirmation
Abnormal liver function and hemodynamic decompensation:
Aggressive therapy to restore hepatic blood flow and decrease hepatic congestion
In setting of elevated international normalized ratio (INR), which is not due to warfarin administration8:
Consider treatment prior to MCS implantation.
Optimize nutrition and right-side intracardiac filling pressures.
Note: Antiplatelet therapy is typically held for 4 to 7 days prior to LVAD implantation; INR should be normalized to minimize risk of bleeding.
Preoperative abnormal coagulation is common due to hepatic dysfunction.22
Obtain chest radiograph and arterial blood gas.
Invasive determination of intracardiac filling pressures
Management of right ventricular (RV) dysfunction
Hospitalization for aggressive therapeutic options:
Pulmonary/RV afterload reduction
Short-term temporary MCS
Computed tomography (CT) imaging or magnetic resonance imaging (MRI):
Prior to MCS implantation
In setting of prior surgery or suspected thoracic anomalies
Malnutrition is common in patients with end-stage HF.22
Approximately half of all patients with advanced HF experience weight loss
Progressive wasting with concomitant inflammatory response
Body mass index (BMI) <24, weight loss of at least 5 kg over 6 months, and current weight <85% of ideal body weight
Compromised immune function
Poor wound healing
Skeletal muscle atrophy that negatively impacts potential for postoperative recovery
Increased morbidity and mortality
Malnutrition may be due to a number of medical and psychological factors including23 the following:
Nausea subsequent to delayed gastric emptying
Chronic, low-grade, systemic inflammation
Excess production of gastric acid associated with emotional and physical stressors
Decreased tolerance of food or medications
Poor eating habits
A registered dietician, pharmacist, and physician with expertise in nutrition are key members of the interdisciplinary MCS team.24
Potential assessment tools23
Anthropometric assessment: BMI (may be misleading due to fluid retention)
Diet and weight history
Biochemical assessment: serum albumin and prealbumin; C-reactive protein8:
Note: results may be influenced by many factors.23
Consider nutritional support for patients with malnutrition.8
Potential nutritional support options:
Oral nutritional supplements
In the setting of severe malnutrition, consider delaying MCS implantation and optimizing nutritional status if the patient’s clinical status permits.8
Infection risk: prior to MCS implantation:
Remove all unnecessary lines and catheters.
Dental assessment and remedial treatment, time, and patient’s clinical status permitting.
Nasal swab to screen for methicillin-resistant Staphylococcus aureus; if results are positive, administer topical antibiotic treatment.
Active infection: administer appropriate antibiotic therapy per infectious disease specialist.
TABLE 10-5 Nutritional Recommendations for Ventricular Assist Device Patients