Elsevier

Critical Care Clinics

Volume 30, Issue 3, July 2014, Pages 607-627
Critical Care Clinics

Left Ventricular Assist Device Management and Complications

https://doi.org/10.1016/j.ccc.2014.04.001Get rights and content

Section snippets

Key points

  • Mechanical assist devices have emerged as one of the main therapies of advanced heart failure.

  • Patients on long-term LVAD support present unique challenges in the intensive care unit.

  • Managing patients on mechanical circulatory support require basic understanding of the physiology and characteristics of the devices and awareness of its complications.

Heart failure (HF) is one of the most frequent medical diagnoses, with more than 650,000 new patients with HF diagnosed annually and more than 5

Ventricular assist devices

A ventricular assist device (VAD) is a mechanical circulatory device that is used to partially or completely replace the function of a failing heart. The first-generation devices, the HeartMate I and Novacor, had pulsatile flow, trying to mimic the normal blood flow that the heart produces. These devices were shown to increase survival and quality of life of patients with end-stage HF compared with optimal medical therapy but had clear limitations. The primary limitation was the lack of

Basic VAD management

Pulsatile devices depend on adequate preload, a fixed stroke volume, and rate to determine pump flow. In contrast, continuous flow pumps depend on a pressure difference across the pump to determine the pump flow. The pressure differential or head pressure is the systemic blood pressure – LV pressure. The pump flow is also determined by the LVAD speed in revolutions per minute (RPM), which is the only parameter on an LVAD that can be adjusted. The combination of head pressure plus LVAD speed

Interpreting the LVAD parameters

Each type of assist device has several parameters that can be informative in monitoring the patient and in identifying certain complications of the devices, such as VAD thrombosis, obstruction, suction events, hydration, and valvular insufficiency. Here, we focus on the most frequently used assist devices, HeartMate II and HeartWare HVAD.

Parameters of HeartMate II

The device parameters include speed, power, pulsatility index (PI), and flow. Power and pump speed (RPM) are the only direct measurement of the device, and both the flow and the PIs are estimated values determined from power and pump speed.

Parameters of HeartWare HVAD

The HeartWare HVAD device estimates the blood flow rate using the characteristics (electrical current, RPM) and blood viscosity. Viscosity is calculated from the patient’s hematocrit level, and the patient’s updated hematocrit level should be entered in to the monitor to receive the flow estimation.

LVAD Thrombosis

VAD thrombosis is one of the most devastating complications of LVAD, previously described to occur in 2% of the patients treated with VAD as BTT15 and 4% of patients treated as DT.7 This prevalence is likely substantially higher, with an increasing number of cases in the last 2 years.16

By definition, VAD thrombosis is the development of a blood clot in one of the components of the VAD, including the inflow cannula, outflow cannula, and the rotor/propeller. Several risk factors have been linked

Ventricular arrhythmias

Ventricular arrhythmias (ventricular tachycardia and fibrillation) are common, affecting 30% of patients treated with long-term LVAD support.37 The arrhythmias tend to occur early after device implantation and are 10 times more likely to occur in the first month.38 Several risk factors are correlated with the occurrence of ventricular arrhythmias in patients with LVAD; the most prominent factor is a history of ventricular arrhythmias before LVAD support.37

Although ventricular arrhythmias can be

Summary

Patients on long-term LVAD support present unique challenges in the intensive care unit. It is crucial to always know the status of end-organ perfusion, and this may require invasive hemodynamic monitoring with a systemic arterial and PA catheter. Depending on the indication for LVAD support (bridge to decision or cardiac transplantation vs DT), it is also important to readdress goals of care with the patient (if possible) and their family after major events have occurred that challenge the

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