a first lead provides therapeutic stimulation to the heart and includes a first mechanical sensor that measures physical contraction and relaxation of the heart . a controller induces delivery of therapeutic stimulation via the first lead . the controller receives signals from the first mechanical sensor indicative of the contraction and relaxation ; develops a template signal that corresponds to the contraction and relaxation ; and uses the template signal to modify the delivery of therapeutic stimulations . in another arrangement , a second lead , with a second mechanical sensor also provides signals to the controller indicative of contraction and relaxation . the first mechanical sensor is adapted to be positioned at the interventricular septal region of the heart , and the second mechanical sensor is adapted to be positioned in the lateral region of the left ventricle . the controller processes the signals from the first mechanical sensor and the second mechanical sensor to develop a dysynchrony index .