Mechanical Circulatory Support

Mechanical Circulatory Support

Suzanne R. Chillcott, RN, BSN

Leslie Hazard, RN, MS, ANP-BC, CNS


A. Scope of the problem

  • 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.

B. Overview

  • 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:

      • Approximately 35% of adult heart transplant recipients were bridged to transplant with LVADs2

      • Approximately 23% of pediatric recipients were bridged to transplantation with a ventricular assist device or total artificial heart.3

  • 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).


A. MCS devices can be categorized according to the type of flow, duration of support, anatomic positioning of the pump, and ventricle(s) supported.

B. Type of flow:

  • 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).

C. Duration of support:

  • Short-term devices: those devices that can be used to support a patient for a few hours to days, such as

    • IABP

    • 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.

D. Anatomic positioning of pump:

  • Internal (intracorporeal) versus external (paracorporeal) positioning

E. Ventricle(s) supported:

  • An LVAD supports the left ventricle.

    • LVADs are the most common type of devices used for long-term support.

    • Examples:

      • 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

    • Berlin Heart

    • Short-term devices:

      • CentriMag

      • Maquet VAD

      • Medtronic VAD

  • A biventricular assist device (BiVAD) supports both ventricles; examples include

    • Thoratec paracorporeal ventricular assist device

    • Berlin Heart

    • Short-term support devices:

      • Bilateral CentriMag

      • Maquet VAD

      • Medtronic VAD

    FIGURE 10-1 HeartMate II LVAD with Pocket Controller. (Picture provided by Thoratec Inc.)

  • 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

FIGURE 10-2 HeartWare HVAD. (Picture provided by HeartWare Inc.)


A. Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) data indicate a 1-year actuarial survival rate of 80% and a 2-year actuarial survival rate of 70% following implantation of a continuous flow device (LVADs, BiVADs)

B. 1-year survival is highest for continuous flow LVADs (81%) followed in decreasing order by pulsatile flow LVADs (65%), total artificial heart (59%), continuous flow BiVADs (57%), and pulsatile flow BiVADs (45%)


A. LVADs assist the failing heart by

  • 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

B. RVADs assist the failing heart by

  • Unloading the right ventricle

  • Augmenting pulmonary circulation

  • Improving preload to left ventricle


A. An interdisciplinary team identifies patients who could benefit from transplantation or LVAD implantation as BTT or DT.

  • 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

B. Decisions regarding MCS are typically based on

  • 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:

    • See Table 10-2 for ISHLT classes of recommendations and levels of evidence.9

  • 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

      Evaluation process

      Assess patient for any reversible causes of heart failure.



      Assess patient for potential transplant candidacy.



      Clinical classification

      Assess patient’s New York Heart Association functional class.



      Determine patient’s Interagency Registry for Mechanically Assisted Support profile.



      Risk stratification

      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:

      • Heart transplantation

      • 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 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.

C. Decisions regarding patient selection and timing of LVAD implantation for DT are often guided by data from:

  • The Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) trial14

  • The Heart Mate II Trial15

  • INTERMACS Registry16

D. Patients undergo a rigorous interdisciplinary evaluation of cardiovascular, noncardiovascular, and psychosocial factors that could influence postoperative outcomes.8

E. See Table 10-3 for the ISHLT Guidelines for MCS: Contraindications and Recommendations


A. As part of the informed consent process, topics discussed with the patient/family include, but are not limited to, the following:

  • Patient’s and family’s goals and expectations

  • Patient’s prognosis

  • 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)



    Permanent dialysis



    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 pregnancy



    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 Accessed June 27, 2015.

  • Necessary social support, including caregiver responsibilities and burden

  • Postoperative recovery, including pain management

  • Postimplant restrictions

  • Medications while MCS is in place

  • Device-specific instructions

  • Long-term care implications

  • Potential for survival following serious complications

  • Endpoints for and alternatives to MCS therapy

  • Advance directives

  • 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)

B. Assessment of the patient’s current quality of life can assist the patient in the decision-making process.

C. Although seemingly counterintuitive, an interdisciplinary palliative care consult at this time may be useful for19:

  • 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

D. It is beneficial for both patients and their caregivers to meet with current LVAD patients and their caregivers to get a better understanding of what it is like to live with an LVAD.

E. Given the interplay of complex clinical, psychosocial, and ethical issues associated with VAD implantation, Petrucci and colleagues20 proposed a triphase model for the informed consent process (Table 10-4). The timing and duration of each phase depends on the clinical status of the patient and is tailored to the patient’s and family’s needs.

TABLE 10-4 Triphase Model for Ventricular Assist Device Patient/Family Education and Informed Consent Process




Phase 1: initial information

Surgical intervention

Reason for VAD implantation

Implications of elective vs. urgent VAD implantation

Anticipated time of VAD implantation

Specific devices available at institution

Potential for device failure

Potential need for device replacement

Potential complications

Device technology

Current device technology

Risks, benefits, possible outcomes

Potential need for additional surgical procedures

VAD as “rescue” device rather than “cure” for heart failure

Morbidity, mortality rates

Expected recovery

Anticipated length of hospitalization Recovery trajectory

Potential modification of care plan

Plan of care may change depending on physical, hemodynamic, or neurologic needs.

Potential for change from “bridge to transplantation” to “destination therapy”

Potential unexpected events: technical failure, pump replacement, withdrawal of device

Phase II: preimplant information

Care planning

Psychological and social aspects of “life with a VAD”

Preparation of advance directives, living will, or health care power of attorney

Appointing a decision-maker

Potential need for assessment of patient’s mental capacity (e.g., neurologic and/or psychiatric evaluations)

Appointment of family spokesperson to facilitate communication between interdisciplinary team and patient’s family/friends

Religious or cultural preferences

Patient’s preferences in the event of withdrawal of VAD support

Conflict resolution

Potential for ethics consultation in the event of unresolvable conflicts between family expectations and patient’s clinical status and prognosis

Phase III: VAD-specific end-of-life care

Plan for palliative care

Potential postimplant end-of-life scenarios (e.g., device failure)

Patient’s preferences regarding potential aggressive management, palliative, or comfort care

Definition and discussion of do not resuscitate/do not intubate orders

Palliative care in home, hospital, hospice, other facility

Plan for withdrawal of VAD support

Development of acceptable device withdrawal process for patient and family

* Timing and duration of each phase depends on the clinical status of the patient and is tailored to the patient’s and family’s needs.

From Petrucci RJ, Benish LA, Carrow BL, et al. Ethical considerations for ventricular assist device support: a 10-point model. ASAIO J. 2011;57(4):268-273.

F. With the increasing use of LVADs, numerous LVAD-related Internet, print, and multimedia educational resources materials are now available to patients and families.

  • 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.


A. Renal function8

  • 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:

    • Serum creatinine

    • Blood urea nitrogen

    • 24-hour urine for creatinine clearance and protein

B. Hepatic function

  • Screen for cirrhosis with ultrasound of the liver in the setting of:

    • History of liver disease

    • Abnormal liver function tests

    • Chronic right heart failure

    • Fontan physiology

  • Suspected cirrhosis8:

    • Radiologic and tissue confirmation

    • Hepatology consult

  • 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

C. Pulmonary function8

  • Obtain chest radiograph and arterial blood gas.

D. Right ventricular function

  • Assessment with:

    • Echocardiogram

    • Invasive determination of intracardiac filling pressures

  • Management of right ventricular (RV) dysfunction

    • Hospitalization for aggressive therapeutic options:

      • Diuresis

      • Ultrafiltration

      • Inotropic support

      • Pulmonary/RV afterload reduction

      • IABP

      • Short-term temporary MCS

E. Thoracic anatomy8

  • Computed tomography (CT) imaging or magnetic resonance imaging (MRI):

    • Prior to MCS implantation

    • In setting of prior surgery or suspected thoracic anomalies

F. Nutritional status

  • Malnutrition is common in patients with end-stage HF.22

    • Approximately half of all patients with advanced HF experience weight loss

    • Cardiac cachexia23:

      • 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

    • Sequelae of malnutrition include22,23 the following:

      • Compromised immune function

      • Poor wound healing

      • Skeletal muscle atrophy that negatively impacts potential for postoperative recovery

      • Prolonged hospitalization

      • Increased morbidity and mortality

  • Malnutrition may be due to a number of medical and psychological factors including23 the following:

    • Anorexia

    • Early satiety

    • 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

    • Physical examination

    • Handgrip assessment

    • 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

  • Nutritional support8:

    • Consider nutritional support for patients with malnutrition.8

    • Potential nutritional support options:

      • Oral nutritional supplements

      • Enteral nutrition

      • Parenteral nutrition

  • In the setting of severe malnutrition, consider delaying MCS implantation and optimizing nutritional status if the patient’s clinical status permits.8

  • See Table 10-5 Nutrition Recommendations for VAD Patients.23,25,26

G. Infection8

  • 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


Normal Weight


Energy requirements

30-35 kcal/kg


Resting metabolic rate + 15%-25% minimal, physical activity; additional 10% for hypermetabolism

Recommendation: metabolic cart to determine resting energy expenditure by measuring oxygen consumption and carbon dioxide production.

Average: 21 kcal/kg actual weight

Protein requirements

1-1.5 g/kg

1.5-2.0 g/kg of ideal body weight


2 g sodium


1.5-2.0 L


Small, frequent meals

Encourage protein intake to meet metabolic demand.

Enteral nutrition

Consider in following setting: severely ill patients who cannot start on oral diet within 24-48 h of ICU admission; hemodynamically unstable patients, particularly malnourished patients and/or those on vasopressors

Consider placement of feeding tube into small intestine

Hypo-osmolar, fiber-free formula, concentrated (i.e., 1.5 kcal/mL) In setting of enteral intolerance or ischemic bowel: initial rate = 10-20 mL/h


B vitamin: supplement in setting of poor oral intake or known deficiency

Vitamin D: supplement in setting of known deficiency

Zinc: supplement in setting of known deficiency

Adapted from Montgomery TD, Cohen AE, Garnick J, et al. Nutrition assessment, care, and considerations of ventricular assist device patients. Nutr Clin Pract. 2012;27(2):352-362; Anderegg BA, Worrall C, Barbour E, et al. Comparison of resting energy prediction methods with measured resting energy expenditure in obese, hospitalized adults. J Parenter Enteral Nutr. 2009;33(2):168-175; Glynn CC, Greene GW, Winkler MF, et al. Predictive versus measured energy expenditure using limits-of-agreement analysis in hospitalized, obese patients. J Parenter Enteral Nutr. 1999;23(3):147-154.

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Oct 27, 2018 | Posted by in NURSING | Comments Off on Mechanical Circulatory Support
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