A system for ablating cardiac tissue, the system comprising: a medical device including: an elongate body defining a distal portion, a proximal portion, and a lumen therebetween; an expandable treatment element coupled to the distal portion of the elongate body; and a sensing component defining a proximal portion and a distal portion, the sensing component being slidably disposed within the elongate body lumen and having one or more mapping elements and a pressure sensor disposed on the distal portion, the pressure sensor being distal of the expandable treatment element and proximal of the one or more mapping elements, the pressure sensor being configured to: record a first blood pressure measurement within a pulmonary vein before the expandable element is positioned in contact with a pulmonary vein ostium; and record a second blood pressure measurement within the pulmonary vein after the expandable element is in contact with the pulmonary vein ostium; and a processor in communication with the expandable treatment element and sensing component, the pressure sensor transmitting blood pressure measurements to the processor, the processor configured to: receive the first and second blood pressure measurements from the pressure sensor; and compare the second blood pressure measurement to the first blood pressure measurement to determine substantial occlusion of the pulmonary vein by the treatment element when the second blood pressure measurement is within a first percentage difference from the first blood pressure measurement and to determine partial occlusion of the pulmonary vein when the second blood pressure measurement is within a second percentage difference from the first blood pressure measurement, the first percentage difference being higher than the second percentage difference a medical device including: an elongate body defining a distal portion, a proximal portion, and a lumen therebetween; an expandable treatment element coupled to the distal portion of the elongate body; and a sensing component defining a proximal portion and a distal portion, the sensing component being slidably disposed within the elongate body lumen and having one or more mapping elements and a pressure sensor disposed on the distal portion, the pressure sensor being distal of the expandable treatment element and proximal of the one or more mapping elements, the pressure sensor being configured to: record a first blood pressure measurement within a pulmonary vein before the expandable element is positioned in contact with a pulmonary vein ostium; and record a second blood pressure measurement within the pulmonary vein after the expandable element is in contact with the pulmonary vein ostium; and an elongate body defining a distal portion, a proximal portion, and a lumen therebetween; an expandable treatment element coupled to the distal portion of the elongate body; and a sensing component defining a proximal portion and a distal portion, the sensing component being slidably disposed within the elongate body lumen and having one or more mapping elements and a pressure sensor disposed on the distal portion, the pressure sensor being distal of the expandable treatment element and proximal of the one or more mapping elements, the pressure sensor being configured to: record a first blood pressure measurement within a pulmonary vein before the expandable element is positioned in contact with a pulmonary vein ostium; and record a second blood pressure measurement within the pulmonary vein after the expandable element is in contact with the pulmonary vein ostium; and record a first blood pressure measurement within a pulmonary vein before the expandable element is positioned in contact with a pulmonary vein ostium; and record a second blood pressure measurement within the pulmonary vein after the expandable element is in contact with the pulmonary vein ostium; and a processor in communication with the expandable treatment element and sensing component, the pressure sensor transmitting blood pressure measurements to the processor, the processor configured to: receive the first and second blood pressure measurements from the pressure sensor; and compare the second blood pressure measurement to the first blood pressure measurement to determine substantial occlusion of the pulmonary vein by the treatment element when the second blood pressure measurement is within a first percentage difference from the first blood pressure measurement and to determine partial occlusion of the pulmonary vein when the second blood pressure measurement is within a second percentage difference from the first blood pressure measurement, the first percentage difference being higher than the second percentage difference receive the first and second blood pressure measurements from the pressure sensor; and compare the second blood pressure measurement to the first blood pressure measurement to determine substantial occlusion of the pulmonary vein by the treatment element when the second blood pressure measurement is within a first percentage difference from the first blood pressure measurement and to determine partial occlusion of the pulmonary vein when the second blood pressure measurement is within a second percentage difference from the first blood pressure measurement, the first percentage difference being higher than the second percentage difference