Pump thrombosis and dynamic outflow graft compression: complications in left ventricular assist device therapy

Over the past decade, left ventricular assist device (VAD) therapy has become more prevalent and increasingly safe. Severe complications, such as VAD pump thrombosis and outflow graft obstruction, are rare, yet still associated with high morbidity and mortality. Clinical presentation, VAD alarm and log files, laboratory analysis, and non-invasive cardiac imaging are crucial for establishing the correct diagnosis and determining clinical management. Early intervention is critical to prevent adverse cardiac remodelling or VAD pump failure

An in vitro lung model to assess true shunt fraction by multiple inert gas elimination

The Multiple Inert Gas Elimination Technique, based on Micropore Membrane Inlet Mass Spectrometry, (MMIMS-MIGET) has been designed as a rapid and direct method to assess the full range of ventilation-to-perfusion (V/Q) ratios. MMIMS-MIGET distributions have not been assessed in an experimental setup with predefined V/Q-distributions. We aimed (I) to construct a novel in vitro lung model (IVLM) for the simulation of predefined V/Q distributions with five gas exchange compartments and (II) to correlate shunt fractions derived from MMIMS-MIGET with preset reference shunt values of the IVLM. Five hollow-fiber membrane oxygenators switched in parallel within a closed extracorporeal oxygenation circuit were ventilated with sweep gas (V) and perfused with human red cell suspension or saline (Q). Inert gas solution was infused into the perfusion circuit of the gas exchange assembly. Sweep gas flow (V) was kept constant and reference shunt fractions (IVLM-S) were established by bypassing one or more oxygenators with perfusate flow (Q). The derived shunt fractions (MM-S) were determined using MIGET by MMIMS from the retention data. Shunt derived by MMIMS-MIGET correlated well with preset reference shunt fractions. The in vitro lung model is a convenient system for the setup of predefined true shunt fractions in validation of MMIMS-MIGET

Bland-Altman analysis with saline as priming fluid.

<p>Bland-Altman analysis of MMIMS-MIGET based shunt fraction–with saline as priming fluid (MM-SNS) on predefined in vitro lung model shunt (IVLM-SNS). Bias ± precision (2 SD) was -0.04 00B1 0.12 with 95% limits of agreement (dashed) of -0.154 and 0.082.</p

Schematic of in vitro lung model setup.

<p>Schematic of in vitro lung model setup.</p

Linear regression analysis with saline as priming fluid.

<p>Linear regression analysis for MMIMS-MIGET shunt fraction–with saline as priming fluid (MM-SNS) on predefined in vitro lung model shunt (IVLM-SNS): MM-SNS = 0.91*IVLM-SNS +0.005 (r² = 0.99, P< 0.0001). Duplicate data from 0 to 0.8 model shunt fractions included. Solid line = linear regression; Dashed line = line of identity.</p

Linear regression analysis with blood as priming fluid.

<p>Linear regression analysis for MMIMS-MIGET based shunt fraction–with blood as priming fluid (MM-SRBC) on predefined in vitro lung model shunt (IVLM-SRBC): MM-SRBC = 0.87*IVLM-SRBC-0.02 (r2 = 0.96, P< 0.0001). Duplicate data from 0 to 0.8 model shunt fractions included. Solid line = linear regression; Dashed line = line of identity.</p

An in vitro lung model to assess true shunt fraction by multiple inert gas elimination

The Multiple Inert Gas Elimination Technique, based on Micropore Membrane Inlet Mass Spectrometry, (MMIMS-MIGET) has been designed as a rapid and direct method to assess the full range of ventilation-to-perfusion (V/Q) ratios. MMIMS-MIGET distributions have not been assessed in an experimental setup with predefined V/Q-distributions. We aimed (I) to construct a novel in vitro lung model (IVLM) for the simulation of predefined V/Q distributions with five gas exchange compartments and (II) to correlate shunt fractions derived from MMIMS-MIGET with preset reference shunt values of the IVLM. Five hollow-fiber membrane oxygenators switched in parallel within a closed extracorporeal oxygenation circuit were ventilated with sweep gas (V) and perfused with human red cell suspension or saline (Q). Inert gas solution was infused into the perfusion circuit of the gas exchange assembly. Sweep gas flow (V) was kept constant and reference shunt fractions (IVLM-S) were established by bypassing one or more oxygenators with perfusate flow (Q). The derived shunt fractions (MM-S) were determined using MIGET by MMIMS from the retention data. Shunt derived by MMIMS-MIGET correlated well with preset reference shunt fractions. The in vitro lung model is a convenient system for the setup of predefined true shunt fractions in validation of MMIMS-MIGET