Pulmonary Capillary Recruitment Is Attenuated Post Left Ventricular Assist Device Implantation

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There is limited knowledge of pulmonary physiology and pulmonary function after continuous flow-left ventricular assist device (CF-LVAD) implantation. Therefore, this study investigated whether CF-LVAD influenced pulmonary circulation by assessing pulmonary capillary blood volume and alveolar-capillary conductance in addition to pulmonary function in patients with heart failure. Seventeen patients with severe heart failure who were scheduled for CF-LVAD implantation (HeartMate II, III, Abbott, Abbott Park, IL or Heart Ware, Medtronic, Minneapolis, MN) participated in the study. They underwent pulmonary function testing (measures of lung volumes and flow rates) and unique measures of pulmonary physiology using a rebreathe technique that quantified the diffusing capacity of the lungs for carbon monoxide (DLCO) and diffusing capacity of the lungs for nitric oxide before and 3 months after CF-LVAD implantation. After CF-LVAD, pulmonary function was not significantly changed (p >0.05). For lung diffusing capacity, alveolar volume (VA) was not changed (p = 0.47), but DLCO was significantly reduced (p = 0.04). After correcting for VA, DLCO/VA showed a trend toward reduction (p = 0.08). For the alveolar-capillary component, capillary blood volume (Vc) was significantly reduced (p = 0.04), and alveolar-capillary membrane conductance trended toward a reduction (p = 0.06). However, alveolar-capillary membrane conductance/Vc was not altered (p = 0.92). In conclusion, soon after CF-LVAD implantation, Vc is reduced likely because of pulmonary capillary derecruitment, which contributes to the decrease in lung diffusing capacity.

Section snippets

Methods

The present single-center study was a within-subject design, comparing preassessment (before LVAD implantation) and 3 months after implantation. Initially, 20 patients with severe heart failure (HF) who were scheduled for CF-LVAD (HeartMate II or Heart Ware) implantation consented and volunteered to participate in the study; however, only 17 patients completed the 3-month assessment. Preassessment was performed within 7 days before CF-LVAD implantation, and postassessment was performed within

Results

Before CF-LVAD, subjects showed impaired (% predicted) measures of pulmonary function including a reduced FVC, FEV1, FEV1/FVC, and FEF25-75 (Table 2). At 3 months after CF-LVAD, FVC and FEV1 remained marginally reduced but were not different to pre–CF-LVAD baseline values (p = 0.10 and p = 0.37, respectively, Table 2). Furthermore, FEV1/FVC and FEF25-75 were not significantly changed at 3 months after implantation compared with before implantation (p = 0.23 and p = 0.80, respectively, Table 2).

Discussion

In this study, we investigated ways pulmonary function and measures of pulmonary physiology specific to pulmonary circulation were influenced by CF-LVAD implantation. At 3 months after CF-LVAD implantation, pulmonary function was not significantly altered from baseline. However, Vc and Dm were significantly reduced without an alteration in the Dm/Vc ratio, which indicates a reduction in alveolar-capillary recruitment. For lung diffusing capacity, DLCO and DLNO were significantly reduced. Even

Declaration of Competing Interest

The authors have no conflicts of interest to declare.

Availability of data and materials

The data generated and/or analyzed during the present study are not deposited but are available from the corresponding author upon reasonable request.

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  • This study was supported by Mayo Clinic Department of Cardiovascular Diseases (Rochester, Minnesota) and Medtronic (Minneapolis, Minnesota).

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