What is a Left Ventricular Assist Device (LVAD)?

What is a Left Ventricular Assist Device (LVAD)?

A Left Ventricular Assist Device (LVAD) is a surgically implanted mechanical pump that assists the failing left ventricle by drawing blood from the left ventricle and propelling it into the aorta to maintain systemic circulation in patients with advanced heart failure. 1

Device Function and Technology

LVADs are durable mechanical circulatory support devices that incorporate into the patient's circulatory system to augment or supplant native cardiac function. 1 The device consists of:

• An internal pump surgically placed in the chest that connects to the left ventricle and aorta 2
• An external controller that regulates pump speed and function 2
• A driveline that exits through the abdominal wall connecting the internal pump to external power sources 2
• Battery packs or electrical connection for continuous power supply 2

Evolution of Technology

Modern LVADs use continuous-flow technology rather than pulsatile flow, which has dramatically improved outcomes 1:

• Second-generation devices (like HeartMate II) use axial-flow pumps with rotating impellers 1
• Third-generation devices (like HeartMate 3) incorporate magnetically levitated disc technology, substantially reducing pump thrombosis and gastrointestinal bleeding compared to earlier models 1
• These continuous-flow devices result in absent or barely perceptible peripheral pulses and require Doppler ultrasound for blood pressure measurement 3

Clinical Indications

Primary Use Categories

Destination therapy (DT) is now the most common indication, comprising 81% of all LVAD implants in patients with end-stage heart failure who are not transplant candidates 1. The three main strategies are:

1. Bridge to transplantation (BTT): For transplant-eligible patients awaiting donor hearts, with 80% achieving successful bridging at 5 years 4, 5
2. Destination therapy (DT): For non-transplant candidates with expected survival >1 year, to improve symptoms and reduce mortality 4
3. Bridge to candidacy (BTC): To permit recovery of end-organ dysfunction and make initially ineligible patients transplant candidates 4

Specific Clinical Criteria

Patients should meet the following criteria after >2 months of optimal medical therapy 4:

• LVEF <25% with peak VO₂ <12 mL/kg/min on cardiopulmonary exercise testing 4
• ≥3 heart failure hospitalizations in the previous 12 months without obvious precipitating cause 4
• Dependence on continuous intravenous inotropic therapy to maintain adequate organ perfusion 4
• Progressive end-organ dysfunction with worsening renal and/or hepatic function 4
• Severe hemodynamic compromise: pulmonary capillary wedge pressure ≥20 mmHg AND systolic blood pressure ≤80-90 mmHg OR cardiac index ≤2 L/min/m² 4

Clinical Impact and Outcomes

Mortality and Survival Benefits

The landmark REMATCH trial demonstrated a 48% reduction in all-cause mortality with LVADs compared to medical therapy alone, leading to FDA approval for destination therapy 1. Contemporary devices provide:

• Median survival exceeding 5 years in appropriately selected patients 5
• 1-year survival rates ranging from 52.6% (INTERMACS Level 1) to 93.0% (INTERMACS Level 5), with earlier implantation showing superior outcomes 4
• Earlier implantation at INTERMACS Levels 4-5 demonstrates better outcomes than waiting until severe deterioration 4

Quality of Life

Most patients experience a doubling in functional capacity after LVAD implantation, even among those receiving destination therapy 5. The devices provide:

• Symptomatic relief from severe heart failure symptoms 1
• Ability for patient ambulation and hospital discharge with portable power sources 1
• Improved exercise tolerance and daily functioning 5

Unique Clinical Characteristics

Physical Examination Findings

Continuous-flow LVADs produce distinctive examination findings that differ from normal physiology 3:

• Peripheral pulses are typically absent or barely perceptible at radial, femoral, and dorsalis pedis sites 3
• Automated blood pressure cuffs fail because oscillometric methods require pulsatile flow 3
• Manual auscultation is unreliable as Korotkoff sounds are absent or severely diminished 3
• Doppler ultrasound over brachial or radial arteries can detect mean arterial pressure only, not separate systolic/diastolic values 3
• Native S1 and S2 may be present but significantly diminished, with an audible mechanical "hum" from the device 3, 2
• Target mean arterial pressure is 70-90 mmHg for optimal outcomes 3

Complications and Risks

Device-Related Adverse Events

Important potential complications include 2, 6:

• Stroke: More common with newer centrifugal-flow devices (29.7%) compared to axial-flow devices (12.1%) 7
• Gastrointestinal bleeding: Reduced with third-generation magnetically levitated devices 1
• Device infection: Particularly at driveline exit sites 1, 2
• Pump thrombosis: Substantially reduced with HeartMate 3 technology 1
• Right heart failure: Occurs in approximately 34% of patients within 2 years 3
• Aortic insufficiency: Develops in 5.6-35% of patients due to prolonged aortic valve closure 3

Contraindications

Absolute contraindications include 4:

• Active infection
• Severe right ventricular dysfunction with severe tricuspid regurgitation
• Irreversible severe renal or hepatic dysfunction
• Uncertain neurological status after cardiac arrest
• Severe peripheral arterial or cerebrovascular disease

Critical Clinical Pitfalls

The most common mistake is waiting too long to refer patients for LVAD evaluation 4. Earlier implantation in less severely ill patients (INTERMACS 4-5) shows significantly better outcomes than delaying until critical illness (INTERMACS 1-2) 4.

Evaluation of right ventricular function is crucial before implantation, as postoperative RV failure greatly increases perioperative mortality and reduces survival 4. If severe biventricular failure exists, consider BiVAD only for transplant-eligible patients, not for destination therapy 4.

LVADs should only be implanted and managed at specialized centers with trained heart failure physicians, cardiac surgeons, and outpatient LVAD clinics with trained nursing staff 4.

Current Utilization

Nearly 20,000 LVADs have been implanted to date in the United States, at a rate of nearly 2,000 per year 1. The devices have become an increasingly common therapy as technology has improved and indications have expanded 1, 2.