Left Ventricular Volume Index in the Adjustment of Initial Dose of Dobutamine in Heart Failure and Cardiogenic Shock

Inclusion Criteria: * LVEF ≤ 40% documented on echocardiography * BNP\> 500 pg / mL * Need for initiation of dobutamine and signs or symptoms of low cardiac output at admission defined by the presence of 2 or more of the following: * SBP ≤ 95 mmHg * FC\> 100 bpm * Peripheral vasoconstriction, * Cold extremities, * Reference of decrease of urine output, * Nausea, vomiting and food intolerance, * Presence of organic dysfunction Exclusion Criteria: * Pregnancy. * COPD * Hepatical cirrhosis * Atrioventricular block of 2nd or 3rd degree. and. SBP \<80 mmHg or need for vasopressor. * Use of definitive pacemaker. * Body mass index greater than 40 kg / m2. * Use of oral anticoagulant. * Acute coronary syndrome. * Indication of use of another inotropic other than dobutamine. * Orotracheal intubation. * Presence of significant pericardial effusion. * Obstruction of left ventricular outflow tract. * Serum creatinine\> 5.0 mg / dL or hemodialysis. * Presence of 2 or more clinical / laboratory / radiological criteria of infection