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Exercise gas exchange in continuous-flow left ventricular assist device recipients.

ABSTRACT: Exercise ventilation/perfusion matching in continuous-flow left ventricular assist device recipients (LVAD) has not been studied systematically. Twenty-five LVAD and two groups of 15 reduced ejection fraction chronic heart failure (HFrEF) patients with peak VO2 matched to that of LVAD (HFrEF-matched) and ?14 ml/kg/min (HFrEF?14), respectively, underwent cardiopulmonary exercise testing with arterial blood gas analysis, echocardiogram and venous blood sampling for renal function evaluation. Arterial-end-tidal PCO2 difference (P(a-ET)CO2) and physiological dead space-tidal volume ratio (VD/VT) were used as descriptors of alveolar and total wasted ventilation, respectively. Tricuspid annular plane systolic excursion/pulmonary artery systolic pressure ratio (TAPSE/PASP) and blood urea nitrogen/creatinine ratio were calculated in all patients and used as surrogates of right ventriculo-arterial coupling and circulating effective volume, respectively. LVAD and HFrEF-matched showed no rest-to-peak change of P(a-ET)CO2 (4.5±2.4 vs. 4.3±2.2 mm Hg and 4.1±1.4 vs. 3.8±2.5 mm Hg, respectively, both p >0.40), whereas a decrease was observed in HFrEF?14 (6.5±3.6 vs. 2.8±2.0 mm Hg, p <0.0001). Rest-to-peak changes of P(a-ET)CO2 correlated to those of VD/VT (r = 0.70, p <0.0001). Multiple regression indicated TAPSE/PASP and blood urea nitrogen/creatinine ratio as independent predictors of peak P(a-ET)CO2. LVAD exercise gas exchange is characterized by alveolar wasted ventilation, i.e. hypoperfusion of ventilated alveoli, similar to that of advanced HFrEF patients and related to surrogates of right ventriculo-arterial coupling and circulating effective volume.

SUBMITTER: Mezzani A

PROVIDER: S-EPMC5983474 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Exercise gas exchange in continuous-flow left ventricular assist device recipients.

Mezzani Alessandro A Pistono Massimo M Agostoni Piergiuseppe P Giordano Andrea A Gnemmi Marco M Imparato Alessandro A Temporelli Pierluigi P Corrà Ugo U

PloS one 20180601 6

Exercise ventilation/perfusion matching in continuous-flow left ventricular assist device recipients (LVAD) has not been studied systematically. Twenty-five LVAD and two groups of 15 reduced ejection fraction chronic heart failure (HFrEF) patients with peak VO2 matched to that of LVAD (HFrEF-matched) and ≥14 ml/kg/min (HFrEF≥14), respectively, underwent cardiopulmonary exercise testing with arterial blood gas analysis, echocardiogram and venous blood sampling for renal function evaluation. Arter ...[more]

PMID: 29856742

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Project description:BACKGROUND:Left ventricular assist devices (LVADs) are an established treatment for end stage heart failure patients. As LVADs do not currently respond to exercise demands, attention is also directed towards improvements in exercise capacity and resulting quality of life. The aim of this study was to explore hemodynamic responses observed during maximal exercise tests to infer underlying patient status and therefore investigate possible diagnostics from LVAD derived data and advance the development of physiologically adaptive LVAD controllers. METHODS:High resolution continuous LVAD flow waveforms were recorded from 14 LVAD patients and evaluated at rest and during maximum bicycle exercise tests (n = 24). Responses to exercise were analyzed in terms of an increase (↑) or decrease (↓) in minimum (QMIN), mean (QMEAN), maximum flow (QMAX) and flow pulsatility (QP2P). To interpret clinical data, a cardiorespiratory numerical simulator was used that reproduced patients' hemodynamics at rest and exercise. Different cardiovascular scenarios including chronotropic and inotropic responses, peripheral vasodilation, and aortic valve pathologies were simulated systematically and compared to the patients' responses. RESULTS:Different patients' responses to exercise were observed. The most common response was a positive change of ΔQMIN↑ and ΔQP2P↑ from rest to exercise (70% of exercise tests). Two responses, which were never reported in patients so far, were distinguished by QMIN↑ and QP2P↓ (observed in 17%) and by QMIN↓ and QP2P↑ (observed in 13%). The simulations indicated that the QP2P↓ can result from a reduced left ventricular contractility and that the QMIN↓ can occur with a better left ventricular contractility and/or aortic insufficiency. CONCLUSION:LVAD flow waveforms determine a patients' hemodynamic "fingerprint" from rest to exercise. Different waveform responses to exercise, including previously unobserved ones, were reported. The simulations indicated the left ventricular contractility as a major determinant for the different responses, thus improving patient stratification to identify how patient groups would benefit from exercise-responsive LVAD control.

Project description:BackgroundVasoplegia after routine cardiac surgery is associated with severe postoperative complications and increased mortality. It is also prevalent in patients undergoing implantation of pulsatile flow left ventricular assist devices (LVAD). However, less is known regarding vasoplegia after implantation of newer generations of continuous flow LVADs (cfLVAD). We aim to report the incidence, impact on outcome and predictors of vasoplegia in these patients.MethodsAdult patients scheduled for primary cfLVAD implantation were enrolled into a derivation cohort (n?=?118, 2006-2013) and a temporal validation cohort (n?=?73, 2014-2016). Vasoplegia was defined taking into consideration low mean arterial pressure and/or low systemic vascular resistance, preserved cardiac index and high vasopressor support. Vasoplegia was considered after bypass and the first 48?h of ICU stay lasting at least three consecutive hours. This concept of vasoplegia was compared to older definitions reported in the literature in terms of the incidence of postoperative vasoplegia and its association with adverse outcomes. Logistic regression was used to identify independent predictors. Their ability to discriminate patients with vasoplegia was quantified by the area under the receiver operating characteristic curve (AUC).ResultsThe incidence of vasoplegia was 33.1% using the unified definition of vasoplegia. Vasoplegia was associated with increased ICU length-of-stay (10.5 [6.9-20.8] vs 6.1 [4.6-10.4] p?=?0.002), increased ICU-mortality (OR 5.8, 95% CI 1.9-18.2) and one-year-mortality (OR 3.9, 95% CI 1.5-10.2), and a higher incidence of renal failure (OR 4.3, 95% CI 1.8-10.4). Multivariable analysis identified previous cardiothoracic surgery, preoperative dopamine administration, preoperative bilirubin levels and preoperative creatinine clearance as independent preoperative predictors of vasoplegia. The resultant prediction model exhibited a good discriminative ability (AUC 0.80, 95% CI 0.71-0.89, p?<? 0.01). Temporal validation resulted in an AUC of 0.74 (95% CI 0.61-0.87, p?<? 0.01).ConclusionsIn the era of the new generation of cfLVADs, vasoplegia remains a prevalent (33%) and critical condition with worse short-term outcomes and survival. We identified previous cardiothoracic surgery, preoperative treatment with dopamine, preoperative bilirubin levels and preoperative creatinine clearance as independent predictors.

Project description:BackgroundAdvanced heart failure therapies such as left ventricular assist device (LVAD) implantation require intricate follow-up and complex care. We sought to explore the burden of psychosocial risk factors among patients with LVAD and their impact on postimplant outcomes using the Interagency Registry for Mechanically Assisted Circulatory Support.MethodsAdult patients in the Interagency Registry for Mechanically Assisted Circulatory Support requiring durable LVAD between 2008 and 2017 were included. Individuals were determined to have psychosocial risk if they had one of the following: (1) limited social support; (2) limited cognition; (3) substance abuse (alcohol and drug); (4) severe psychiatric disease (including major depression and other major psychiatric diagnosis); and (5) repeated noncompliance. Univariate and multivariate Cox proportional hazard regression models were used to analyze predictors of survival and complications.ResultsA total of 15 403 continuous-flow LVAD recipients were included. A total of 3163 (20.5%) had one or more psychosocial risk factors. The most prevalent psychosocial risk factor was substance abuse in 1941 (12.6%) recipients. Patients with psychosocial risk factors were significantly younger at LVAD implant, less likely to be White, and less likely to be female compared with those without psychosocial risk, P<0.001 for all. Patients with psychosocial risk were significantly more likely to receive an LVAD as destination therapy, P<0.001. In adjusted models, patients with psychosocial risk were at increased hazards for device-related infection, gastrointestinal bleeding, pump thrombosis, and readmission and reduced hazards for cardiac transplantation (P<0.05 for all). There was no statistically significant difference in survival on pump support or stroke.ConclusionsPsychosocial risk is an important component of patient selection for advanced heart failure therapies. Addressing these specific components may help improve access to advanced therapies and post-LVAD outcomes.

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Exercise gas exchange in continuous-flow left ventricular assist device recipients.

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Exercise gas exchange in continuous-flow left ventricular assist device recipients.

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