title: The left ventricle as a mechanical engine:  from Leonardo da Vinci to the echocardiographic assessment of peak power output-to-left ventricular mass.
abstract: The interpretation of the heart as a mechanical engine dates back to the teachings of Leonardo da Vinci, who was the first to apply the laws of mechanics to the function of the heart. Similar to any mechanical engine, whose performance is proportional to the power generated with respect to weight, the left ventricle can be viewed as a power generator whose performance can be related to left ventricular mass. Stress echocardiography may provide valuable information on the relationship between cardiac performance and recruited left ventricular mass that may be used in distinguishing between adaptive and maladaptive left ventricular remodeling. Peak power output-to-mass, obtained during exercise or pharmacological stress echocardiography, is a measure that reflects the number of watts that are developed by 100 g of left ventricular mass under maximal stimulation. Power output-to-mass may be calculated as left ventricular power output per 100 g of left ventricular mass: 100× left ventricular power output divided by left ventricular mass (W/100 g). A simplified formula to calculate power output-to-mass is as follows: 0.222 × cardiac output (l/min) × mean blood pressure (mmHg)/left ventricular mass (g). When the integrity of myocardial structure is compromised, a mismatch becomes apparent between maximal cardiac power output and left ventricular mass; when this occurs, a reduction of the peak power output-to-mass index is observed.
authors.affiliation: Cardiac, Thoracic and Vascular Department, University of Pisa, Pisa, Italy. f.dini@ao-pisa.toscana.it
authors.forename: Frank L
authors.initials: FL
authors.lastname: Dini
authors.forename: Giacinta
authors.initials: G
authors.lastname: Guarini
authors.forename: Piercarlo
authors.initials: P
authors.lastname: Ballo
authors.forename: Erberto
authors.initials: E
authors.lastname: Carluccio
authors.forename: Maria
authors.initials: M
authors.lastname: Maiello
authors.forename: Paola
authors.initials: P
authors.lastname: Capozza
authors.forename: Pasquale
authors.initials: P
authors.lastname: Innelli
authors.forename: Gian M
authors.initials: GM
authors.lastname: Rosa
authors.forename: Pasquale
authors.initials: P
authors.lastname: Palmiero
authors.forename: Maurizio
authors.initials: M
authors.lastname: Galderisi
authors.forename: Renato
authors.initials: R
authors.lastname: Razzolini
authors.forename: Savina
authors.initials: S
authors.lastname: Nodari
mesh_terms: D002302:Cardiac Output / Q000502:physiology*; D025401:Echocardiography, Stress; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006352:Heart Ventricles / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D008955:Models, Cardiovascular; D016277:Ventricular Function, Left / Q000502:physiology*; D020257:Ventricular Remodeling / Q000502:physiology