Are blood pressures in Left Ventricular Assist Devices (LVADs) measured in Mean Arterial Pressure (MAP)?

Blood Pressure Measurement in Left Ventricular Assist Devices (LVADs)

Blood pressure in LVAD patients is typically measured as Mean Arterial Pressure (MAP) using Doppler ultrasound, with a target range of 70-90 mmHg to optimize outcomes and minimize complications. 1

Why MAP is Used for LVAD Patients

LVADs create continuous blood flow that often eliminates or significantly reduces pulsatility, making traditional blood pressure measurement methods ineffective:

• Continuous-flow LVADs produce minimal pulse pressure, making standard cuff-based measurements unreliable
• Many LVAD patients have no palpable pulse or audible Korotkoff sounds
• MAP provides the most clinically relevant measurement for managing these patients

Standard Measurement Techniques

1. Doppler ultrasound method (gold standard) 1, 2:

   • Place Doppler probe over brachial or radial artery
   • Inflate manual BP cuff above expected systolic pressure
   • Slowly deflate while listening for return of flow
   • The pressure at which flow returns represents the MAP

2. Alternative measurement options:

   • Pulse oximeter-derived measurements can yield MAP values similar to Doppler measurements 2
   • Finger plethysmography (e.g., Finapres® NOVA) shows promise but may have individual-level inaccuracy 3
   • Arterial line for direct measurement (typically only used in immediate post-operative period) 1

Target Blood Pressure Goals

• Optimal MAP target: 70-80 mmHg 1, 4
• MAP ≤75 mmHg is associated with increased risk of stroke and death 4
• MAP ≥80-90 mmHg increases risk of aortic insufficiency development 1, 5

Clinical Implications of Blood Pressure Control

Poor blood pressure control in LVAD patients can lead to serious complications:

• Hypertension risks:

  • Aortic valve fusion and insufficiency
  • Increased afterload reducing LVAD efficiency
  • Increased risk of stroke 1

• Hypotension risks:

  • Reduced end-organ perfusion
  • Increased mortality and stroke risk 4

Management Considerations

• Most LVAD patients require 1-2 antihypertensive medications to maintain target MAP 5
• ACE inhibitors/ARBs (85%) and beta-blockers (30%) are most commonly used 5
• Blood pressure should be regularly monitored at home using Doppler
• LVAD speed adjustments may be necessary to optimize hemodynamics 1

Important Caveats

• Blood pressure measurement technique must be consistent and documented
• Traditional automated blood pressure cuffs significantly underestimate MAP in LVAD patients 2
• Echocardiographic parameters from the LVAD outflow cannula can help predict hemodynamics when direct measurement is challenging 6
• Patients should be educated on proper home blood pressure monitoring techniques

By maintaining MAP within the target range of 70-80 mmHg, clinicians can help minimize complications and optimize outcomes for patients with LVADs.