An apparatus for affecting a pressure within an intrathoracic cavity of a patient, the apparatus comprising: one or more electrodes (322, 324) configured for placement on or near a diaphragm of the patient; a pressure measurement source configured to provide a signal indicative of a pressure within an intrathoracic cavity of the patient; and a controller configured to: detect a cyclic cardiac event within a cardiac cycle of the patient based on a signal obtained from a cardiac event source; deliver an electrical stimulation therapy to a diaphragm of the patient through the one or more electrodes (322, 324) in response to the detection of the cyclic cardiac event, wherein delivery of the electrical stimulation therapy is timed to the detection of the cyclic cardiac event, and the electrical stimulation therapy is defined by a plurality of stimulation parameters that induce a singular caudal-followed-by-cranial movement of the diaphragm within the cardiac cycle, wherein the plurality of stimulation parameters comprises a pulse amplitude in the range of 0.1 to 7.5 volts and a pulse width in the range of 0.1 to 5 milliseconds; derive, from the signal indicative of a pressure within an intrathoracic cavity of the patient, a measure of interest corresponding to a pressure measurement at or near a fiducial point within the cardiac cycle; evaluate the measure of interest against a baseline measure of interest; determine to adjust one or more of the stimulation parameters based on the evaluation; and adjust one or more of the stimulation parameters based on the determining. one or more electrodes (322, 324) configured for placement on or near a diaphragm of the patient; a pressure measurement source configured to provide a signal indicative of a pressure within an intrathoracic cavity of the patient; and a controller configured to: detect a cyclic cardiac event within a cardiac cycle of the patient based on a signal obtained from a cardiac event source; deliver an electrical stimulation therapy to a diaphragm of the patient through the one or more electrodes (322, 324) in response to the detection of the cyclic cardiac event, wherein delivery of the electrical stimulation therapy is timed to the detection of the cyclic cardiac event, and the electrical stimulation therapy is defined by a plurality of stimulation parameters that induce a singular caudal-followed-by-cranial movement of the diaphragm within the cardiac cycle, wherein the plurality of stimulation parameters comprises a pulse amplitude in the range of 0.1 to 7.5 volts and a pulse width in the range of 0.1 to 5 milliseconds; derive, from the signal indicative of a pressure within an intrathoracic cavity of the patient, a measure of interest corresponding to a pressure measurement at or near a fiducial point within the cardiac cycle; evaluate the measure of interest against a baseline measure of interest; determine to adjust one or more of the stimulation parameters based on the evaluation; and adjust one or more of the stimulation parameters based on the determining. detect a cyclic cardiac event within a cardiac cycle of the patient based on a signal obtained from a cardiac event source; deliver an electrical stimulation therapy to a diaphragm of the patient through the one or more electrodes (322, 324) in response to the detection of the cyclic cardiac event, wherein delivery of the electrical stimulation therapy is timed to the detection of the cyclic cardiac event, and the electrical stimulation therapy is defined by a plurality of stimulation parameters that induce a singular caudal-followed-by-cranial movement of the diaphragm within the cardiac cycle, wherein the plurality of stimulation parameters comprises a pulse amplitude in the range of 0.1 to 7.5 volts and a pulse width in the range of 0.1 to 5 milliseconds; derive, from the signal indicative of a pressure within an intrathoracic cavity of the patient, a measure of interest corresponding to a pressure measurement at or near a fiducial point within the cardiac cycle; evaluate the measure of interest against a baseline measure of interest; determine to adjust one or more of the stimulation parameters based on the evaluation; and adjust one or more of the stimulation parameters based on the determining.