( ( ( This ( blood ( vessel constriction ) ) ) ( in ( the heart ) ) ) ( ( can ( cause ( ( decreased ( blood flow ) ) ( to ( ( ( the heart ) , ) ( which ( causes ( chest pain ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT This) (NN blood) (NN vessel) (NN constriction)) (PP (IN in) (NP (DT the) (NN heart)))) (VP (MD can) (VP (VB cause) (NP (NP (VBN decreased) (NN blood) (NN flow)) (PP (TO to) (NP (NP (DT the) (NN heart)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ causes) (NP (NN chest) (NN pain)))))))))) (. .)))
This blood vessel constriction in the heart can cause decreased blood flow to the heart, which causes chest pain.
(ROOT (S (NP (NNP Blood)) (VP (VBP flow) (VP (VB decrease) (SBAR (WHADVP (WRB when)) (S (NP (NN blood) (NNS vessels)) (VP (VBP constrict)))))) (. .)))