Adolescent / Heart Failure / Humans / Left Ventricular Assist Device / Female / Male / Middle Aged / Adult / Public health systems and services research / Survival Rate / Support Group / Prognosis / Mechanical Circulatory Support / Ejection Fraction / Continuous Flow Heart Assist Devices / Predictive value of tests / Brain Natriuretic Peptide / The American / Blood Chemistry / Male / Middle Aged / Adult / Public health systems and services research / Survival Rate / Support Group / Prognosis / Mechanical Circulatory Support / Ejection Fraction / Continuous Flow Heart Assist Devices / Predictive value of tests / Brain Natriuretic Peptide / The American / Blood Chemistry