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The influence of left ventricular assist device inflow cannula position on thrombosis risk.

ABSTRACT: The use of left ventricular assist devices (LVADs) as a treatment method for heart failure patients has been steadily increasing; however, pathological studies showed presence of thrombi around the HeartWare ventricular assist device inflow cannula (IC) in more than 95% of patients after device explantation. Flow fields around the IC might trigger thrombus formation and require further investigation. In this study flow dynamics parameters were evaluated for different patient geometries using computational fluid dynamics (CFD) simulations. Left ventricular (LV) models of two LVAD patients were obtained from CT scans. The LV volumes of Patient 1 (P1) and Patient 2 (P2) were 264 and 114 cm3 with an IC angle of 20° and 9° from the mitral-IC tip axis at the coronal plane. The IC insertion site at the apex was central for P1, whereas it was lateral for P2. Transient CFD simulations were performed over 9 cardiac cycles. The wedge area was defined from the cannula tip to the wall of the LV apex. Mean velocity magnitude and blood stagnation region (volume with mean velocity <5 mm/s) as well as the wall shear stress (WSS) at the IC surface were calculated. Cardiac support resulted in a flow mainly crossing the ventricle from the mitral valve to the LVAD cannula for P2, while the main inflow jet deviated toward the septal wall in P1. Lower WSS at the IC surface and consequently larger stagnation volumes were observed for P2 (P1: 0.17, P2: 0.77 cm3 ). Flow fields around an LVAD cannula can be influenced by many parameters such as LV size, IC angle, and implantation site. Careful consideration of influencing parameters is essential to get reliable evaluations of the apical flow field and its connection to apical thrombus formation. Higher blood washout and lower stagnation were observed for a central implantation of the IC at the apex.

SUBMITTER: Ghodrati M

PROVIDER: S-EPMC7496759 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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The influence of left ventricular assist device inflow cannula position on thrombosis risk.

Ghodrati Mojgan M Maurer Alexander A Schlöglhofer Thomas T Khienwad Thananya T Zimpfer Daniel D Beitzke Dietrich D Zonta Francesco F Moscato Francesco F Schima Heinrich H Aigner Philipp P

Artificial organs 20200506 9

The use of left ventricular assist devices (LVADs) as a treatment method for heart failure patients has been steadily increasing; however, pathological studies showed presence of thrombi around the HeartWare ventricular assist device inflow cannula (IC) in more than 95% of patients after device explantation. Flow fields around the IC might trigger thrombus formation and require further investigation. In this study flow dynamics parameters were evaluated for different patient geometries using com ...[more]

PMID: 32302423

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Project description:BackgroundLeft ventricular assist device (LVAD)-associated infections are major complications that can lead to critical outcomes. The aims of this study were to assess the incidence of and to determine the risk factors for LVAD-associated infections.MethodsWe included all consecutive patients undergoing LVAD implantation between January 1, 2010, and January 1, 2019, in a single institution. Infection-related data were retrospectively collected by review of patient’s medical files. LVAD-associated infections were classified into three categories: percutaneous driveline infections, pocket infections and pump and/or cannula infections.ResultsWe enrolled 72 patients. Twenty-one (29.2%) patients presented a total of 32 LVAD-associated infections. Eight (38.1%) patients had more than one infection. Five (62.5%) pocket infections and one (50.0%) pump and/or cannula infection were preceded by a driveline infection. The median delay between the operation and LVAD-associated infection was 6.5 (1.4–12.4) months. The probability of having a LVAD-associated infection at one year after receiving an implant was 26.6% (95% CI: 17.5–40.5%). Percutaneous driveline infections represented 68.7% of all LVAD-associated infections. Staphylococcus aureus and coagulase-negative staphylococci were the predominant bacteria in LVAD-associated infections (53.1% and 15.6%, respectively). Hospital length of stay (sdHR =1.22 per 10 days; P=0.001) and postoperative hemodialysis (sdHR =0.17; P=0.004) were statistically associated with infection. Colonization with multidrug-resistant bacteria was more frequent in patients with LVAD-associated infections than in others patients (42.9% vs. 15.7%; P=0.013).ConclusionsLVAD-associated infections remain an important complication and are mostly represented by percutaneous driveline infections. Gram-positive cocci are the main pathogens isolated in microbiological samples. Patients with LVAD-associated infections are more frequently colonized with multidrug-resistant bacteria.

Project description:AimsThe risk of HeartMate II (HMII) left ventricular assist device (LVAD) thrombosis has been reported, and serum lactate dehydrogenase (LDH), a biomarker of haemolysis, increases secondary to LVAD thrombosis. This study evaluated longitudinal measurements of LDH post-LVAD implantation, hypothesizing that LDH trends could timely predict future LVAD thrombosis.Methods and resultsFrom October 2004 to October 2014, 350 HMIIs were implanted in 323 patients at Cleveland Clinic. Of these, patients on 339 HMIIs had at least one post-implant LDH value (7996 total measurements). A two-step joint model combining longitudinal biomarker data and pump thrombosis events was generated to assess the effect of changing LDH on thrombosis risk. Device-specific LDH trends were first smoothed using multivariate boosted trees, and then used as a time-varying covariate function in a multiphase hazard model to analyse time to thrombosis. Pre-implant variables associated with time-varying LDH values post-implant using boostmtree were also investigated. Standardized variable importance for each variable was estimated as the difference between model-based prediction error of LDH when the variable was randomly permuted and prediction error without permuting the values. The larger this difference, the more important a variable is for predicting the trajectory of post-implant LDH. Thirty-five HMIIs (10%) had either confirmed (18) or suspected (17) thrombosis, with 15 (43%) occurring within 3 months of implant. LDH was associated with thrombosis occurring both early and late after implant (P < 0.0001 for both hazard phases). The model demonstrated increased probability of HMII thrombosis as LDH trended upward, with steep changes in LDH trajectory paralleling trajectories in probability of pump thrombosis. The most important baseline variables predictive of the longitudinal pattern of LDH were higher bilirubin, higher pre-implant LDH, and older age. The effect of some pre-implant variables such as sodium on the post-implant LDH longitudinal pattern differed across time.ConclusionsLongitudinal trends in surveillance LDH for patients on HMII support are useful for dynamic prediction of pump thrombosis, both early after implant and late. Incorporating upward and downward trends in LDH that dynamically update a model of LVAD thrombosis risk provides a useful tool for clinical management and decisions.

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The influence of left ventricular assist device inflow cannula position on thrombosis risk.

Publications

The influence of left ventricular assist device inflow cannula position on thrombosis risk.

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