( ( ( ( Valve Replacement ) and ) ( Repair ( ( The ( heart 's ) ) ( four valves ) ) ) ) ( ( ( let blood ) ( ( ( in and ) out ) ( of ( ( the ( heart 's ) ) chambers ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Valve) (NNP Replacement)) (CC and) (NP (NP (NNP Repair)) (NP (NP (DT The) (NN heart) (POS 's)) (CD four) (NNS valves)))) (VP (VBD let) (NP (NN blood)) (PP (IN in) (CC and) (IN out) (PP (IN of) (NP (NP (DT the) (NN heart) (POS 's)) (NNS chambers))))) (. .)))
Valve Replacement and Repair The heart's four valves let blood in and out of the heart's chambers.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD four) (NNS valves)) (PP (IN in) (NP (DT the) (NN heart))))) (. .)))