What are the basics of mechanical circulatory support in patients with heart failure, including device selection and management?

Basics of Mechanical Circulatory Support in Heart Failure

Mechanical circulatory support (MCS) is an essential therapeutic option for patients with advanced heart failure, providing hemodynamic stability and improved end-organ perfusion when medical therapy fails. 1

Types of Mechanical Circulatory Support Devices

Short-Term Support Devices

• Intra-Aortic Balloon Pump (IABP): Often the first step in treating cardiogenic shock, providing hemodynamic support through diastolic augmentation of aortic pressure 1
• Percutaneous Devices:
  • Micro-axial flow pumps (e.g., Impella): Provide left, right, or biventricular support through axial flow mechanisms 1
  • TandemHeart: Centrifugal pump system that bypasses the left ventricle by drawing blood from the left atrium and returning it to the femoral artery 1
• Extracorporeal Membrane Oxygenation (ECMO): Provides biventricular support with oxygenation, often used as a "bridge to decision" in acute cardiogenic shock 1

Long-Term Support Devices

• Left Ventricular Assist Devices (LVADs):
  • Continuous flow devices: Current generation with improved durability and fewer complications compared to older pulsatile models 1, 2
  • Implantable pulsatile devices: Earlier generation technology 1
• Right Ventricular Assist Devices (RVADs): Used when right ventricular failure is present 1
• Biventricular Assist Devices (BiVADs): Support both ventricles in biventricular failure 1
• Total Artificial Heart: Complete replacement of the native heart in cases of biventricular failure 3

Clinical Indications and Strategies

Bridge to Recovery (BTR)

• Temporary MCS to maintain circulation after an acute cardiac event until myocardial recovery occurs 1
• Commonly used in postcardiotomy shock, acute myocarditis, or post-cardiac arrest 1

Bridge to Decision (BTD)

• Short-term MCS to stabilize hemodynamics and end-organ function while evaluating for more definitive therapy 1
• Allows time to exclude contraindications for long-term MCS or transplantation 1

Bridge to Candidacy (BTC)

• MCS to improve end-organ function to make previously ineligible patients eligible for heart transplantation 1

Bridge to Transplantation (BTT)

• MCS to support patients at high risk of death while awaiting heart transplantation 1
• Recommended for transplant-eligible patients with end-stage heart failure failing optimal medical therapy 1

Destination Therapy (DT)

• Long-term MCS as an alternative to transplantation for patients ineligible for heart transplant 1
• Beneficial for patients with advanced heart failure, high 1-year mortality, and absence of other life-limiting organ dysfunction 1

Patient Selection

INTERMACS Classification

• INTERMACS Profile 1 (Critical cardiogenic shock): Requires immediate intervention within hours 1
• INTERMACS Profile 2 (Progressive decline on inotropes): Requires intervention within days 1
• INTERMACS Profile 3 (Stable but inotrope dependent): Elective intervention over weeks to months 1
• INTERMACS Profile 4-7: Progressively less urgent, with varying timeframes for intervention 1

Key Considerations for Patient Selection

• Timing: Early referral before development of advanced heart failure (hyponatremia, hypotension, renal dysfunction) is associated with better outcomes 1
• Right Ventricular Function: Careful assessment is essential before durable MCS implantation 1
• Renal Function: Long-term MCS is not recommended in patients with advanced kidney disease unlikely to recover despite improved hemodynamics 1
• Nutritional Status: Assessment is recommended as part of patient evaluation 1
• Psychosocial Factors: Assessment of psychosocial, behavioral, and environmental factors is beneficial for patient selection 1

Management Principles

Hemodynamic Assessment

• Evaluate adequacy of systemic perfusion, volume status, and contributing factors 1
• Monitor cardiac output, filling pressures, and end-organ perfusion 1
• Use echocardiography for biventricular function assessment and monitoring 1

Device Management

• Record device parameters (power, speed, flow, pulsatility) regularly 1
• Monitor for device-related complications including bleeding, infection, thromboembolism, and device failure 4
• Anticoagulation regimens must be tailored to the specific device and clinical situation 4

Multidisciplinary Approach

• Evaluation by a multidisciplinary team is recommended for patient selection 1
• Coordination between implantation centers, local providers, and emergency services is essential 1

Complications and Management

Bleeding

• Major complication in MCS patients due to anticoagulation requirements and acquired von Willebrand syndrome 4
• Requires careful anticoagulation management and monitoring 4

Thrombosis

• Device thrombosis can lead to pump failure or embolic events 4
• Risk varies by device type and clinical indication 4

Infection

• Driveline infections are common complications of durable MCS 2
• Requires preventive measures and prompt treatment 2

Right Ventricular Failure

• Can occur after LVAD implantation, significantly worsening outcomes 1
• May require additional right-sided support 1

Future Directions

• Development of fully implantable devices without transcutaneous drivelines 1
• Improved hemocompatibility to reduce anticoagulation requirements 2
• Miniaturization of devices for less invasive implantation 2
• Enhanced patient selection algorithms to optimize outcomes 2

Special Considerations

• Emergency Situations: Contact the primary MCS team for any patient-related emergencies 1
• End-of-Life Planning: Advance directives should be completed before device implantation 1
• Palliative Care: Important for supporting patients and caregivers, especially after serious complications 1