Some embodiments of a system or method for treating heart tissue can include a control system and catheter device operated in a manner to intermittently occlude a heart vessel for controlled periods of time that provide redistribution of blood flow. In particular embodiments, the system can be configured to provide an estimation of the cumulative effects of the treatment. For example, some embodiments of the system or method can treat myocardium that is at risk of infarction by intermittently altering blood flow in a venous system to induce microcirculation within the myocardium, and can output a cumulative dosage value indicative of a measurement of progress of reducing an infarct size.