BACKGROUND: In patients affected by chronic heart failure (HF) an inappropriate tissues O2 extraction is one of the major determinants of patients’ fatigue during exercise. We tested the hypothesis that an increase of CO through pump speed change in LVAD patients, might be associated with a better O2 muscle metabolism in both rest and exercise conditions. METHODS: Fifteen of 16 LVAD patients enrolled (100% M, mean age 63.8±8.3 years), successfully performed on different days two sub-maximal constant workload cardiopulmonary exercise tests (CPET), one at LVAD speed 2 and one at 4, set up randomly, in which was evaluated O2 kinetic (τ constant). CO and muscle oxygenation were evaluated at rest and during exercise through inert gas rebreathing (IGR) technique and muscle vastus medialis near infrared spectroscopy (NIRS), respectively. NIRS total haemoglobin [HbTot], oxygenated haemoglobin [HbO2] and deoxygenated haemoglobin [HbDO2] concentrations were considered as overall values and as “basal”, at rest, “zenit” and “nadir”, during exercise, values. RESULTS: From 2 to 4 LVAD speed, CO increased from 3.1±0.8 to 3.7±0.7 L/min (p=0.01) and from 5.9±1.3 to 6.6±1.0 L/min (p=0.01) at rest and exercise, respectively. O2 kinetics shows a τ decrease from 68.1±17.1 to 52.3±17.0 (p<0,01), due to increased muscle blood flow and oxygenation, as shown by [HbTot] overall values, that passed from 78.8±24.2 μM/L to 85.8±27.7 μM/L (p=0.07) and by [HbO2] overall values, that passed from 57.9±22.4 μM/L to 65.4±27.4 μM/L (p=0.02). On graphs, values difference between speed 2 and 4 is remarkable, but not yet statistically significant: the [HbTot] and [HbO2] higher values at speed 4 may indicate better perfusion and a lower O2 extraction necessity, confirmed by specular values on [HbDO2]. CONCLUSIONS: : In HF patients a CO increase with a higher LVAD pump speed is associated with an improvement in O2 kinetic and a greater muscle peripheral blood flow and lower O2 extraction at rest and during exercise.
LVAD Pump Speed Increase is Associated with Improvement of Cardiac Output, O2 Kinetic and O2 Muscle Extraction / S. Paolillo, C. Vignati, A. Apostolo, N. Bonini, F. Maria Righini, G. Gerosa, T. Bottio, V. Tarzia Jonida Bejko, P. Agostoni. ((Intervento presentato al 38. convegno ISHLT Annual Meeting tenutosi a Nice nel 2018.
LVAD Pump Speed Increase is Associated with Improvement of Cardiac Output, O2 Kinetic and O2 Muscle Extraction
C. Vignati;P. Agostoni
2018
Abstract
BACKGROUND: In patients affected by chronic heart failure (HF) an inappropriate tissues O2 extraction is one of the major determinants of patients’ fatigue during exercise. We tested the hypothesis that an increase of CO through pump speed change in LVAD patients, might be associated with a better O2 muscle metabolism in both rest and exercise conditions. METHODS: Fifteen of 16 LVAD patients enrolled (100% M, mean age 63.8±8.3 years), successfully performed on different days two sub-maximal constant workload cardiopulmonary exercise tests (CPET), one at LVAD speed 2 and one at 4, set up randomly, in which was evaluated O2 kinetic (τ constant). CO and muscle oxygenation were evaluated at rest and during exercise through inert gas rebreathing (IGR) technique and muscle vastus medialis near infrared spectroscopy (NIRS), respectively. NIRS total haemoglobin [HbTot], oxygenated haemoglobin [HbO2] and deoxygenated haemoglobin [HbDO2] concentrations were considered as overall values and as “basal”, at rest, “zenit” and “nadir”, during exercise, values. RESULTS: From 2 to 4 LVAD speed, CO increased from 3.1±0.8 to 3.7±0.7 L/min (p=0.01) and from 5.9±1.3 to 6.6±1.0 L/min (p=0.01) at rest and exercise, respectively. O2 kinetics shows a τ decrease from 68.1±17.1 to 52.3±17.0 (p<0,01), due to increased muscle blood flow and oxygenation, as shown by [HbTot] overall values, that passed from 78.8±24.2 μM/L to 85.8±27.7 μM/L (p=0.07) and by [HbO2] overall values, that passed from 57.9±22.4 μM/L to 65.4±27.4 μM/L (p=0.02). On graphs, values difference between speed 2 and 4 is remarkable, but not yet statistically significant: the [HbTot] and [HbO2] higher values at speed 4 may indicate better perfusion and a lower O2 extraction necessity, confirmed by specular values on [HbDO2]. CONCLUSIONS: : In HF patients a CO increase with a higher LVAD pump speed is associated with an improvement in O2 kinetic and a greater muscle peripheral blood flow and lower O2 extraction at rest and during exercise.
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