A system for treating heart muscle tissue, comprising: a coronary sinus occlusion catheter including a distal tip portion, a proximal hub portion, a pressure sensor lumen, and a balloon fluid lumen, the distal tip portion of the coronary sinus occlusion catheter comprising an inflatable balloon device configured to occlude a coronary sinus when inflated with fluid via the balloon fluid lumen; and a control system to control the inflation and deflation of the inflatable balloon device for pressure-controlled intermittent coronary sinus occlusion, the control system comprising a display device, a pressure signal input that is adapted to receive a pressure signal indicative of coronary sinus pressure, an electrocardiogram signal input, and a control circuit adapted to activate a pneumatic subsystem to inflate or deflate the inflatable balloon device of the coronary sinus occlusion catheter for a selected period of time based at least in part on the pressure signal indicative of the coronary sinus pressure, wherein the control system is adapted to activate, during an initial period of operation, the inflatable balloon device of the coronary sinus occlusion catheter to intermittently occlude the coronary sinus in a predetermined pattern of occlusion periods and release periods that is independent of the pressure signal indicative of the coronary sinus pressure, and during a second period of operation, to activate the inflatable balloon device of the coronary occlusion catheter to intermittently occlude the coronary sinus in a pattern that is dependent in part on the pressure signal indicative of the coronary sinus pressure. a coronary sinus occlusion catheter including a distal tip portion, a proximal hub portion, a pressure sensor lumen, and a balloon fluid lumen, the distal tip portion of the coronary sinus occlusion catheter comprising an inflatable balloon device configured to occlude a coronary sinus when inflated with fluid via the balloon fluid lumen; and a control system to control the inflation and deflation of the inflatable balloon device for pressure-controlled intermittent coronary sinus occlusion, the control system comprising a display device, a pressure signal input that is adapted to receive a pressure signal indicative of coronary sinus pressure, an electrocardiogram signal input, and a control circuit adapted to activate a pneumatic subsystem to inflate or deflate the inflatable balloon device of the coronary sinus occlusion catheter for a selected period of time based at least in part on the pressure signal indicative of the coronary sinus pressure, wherein the control system is adapted to activate, during an initial period of operation, the inflatable balloon device of the coronary sinus occlusion catheter to intermittently occlude the coronary sinus in a predetermined pattern of occlusion periods and release periods that is independent of the pressure signal indicative of the coronary sinus pressure, and during a second period of operation, to activate the inflatable balloon device of the coronary occlusion catheter to intermittently occlude the coronary sinus in a pattern that is dependent in part on the pressure signal indicative of the coronary sinus pressure.