A technical and data analytic approach to pressure-volume loops over numerous cardiac cycles

Fig 1. Placement of the micromanometer catheter used to generate the pressure-volume (PV) loops. A, Cartoon of PV loop placement showing a left ventricular micromanometer catheter in place, with conceptual delimitations of segmentation. The PV catheter entered the aortic arch from the carotid artery, which is a preferred access point for setup. B, Anteroposterior fluoroscopic image of the chest showing a micromanometer catheter in situ within the left ventricle (LV), placed through a 7F sheath in the left femoral artery, which can be more challenging than carotid or brachial artery access for placement, but it is possible.

Fig 2. Left ventricle (LV) pressure vs volume over time, with continuous pressure-volume (PV) loops (blue) plotted, along with an interpolated PV loop (red), representing the average PV loop from the time period.

Supplementary Fig 1. Pre- and post-clean pressure-volume (PV) loop data: theta vs time. Each colored line represents one loop, converted to polar coordinates. Each loop starts at theta = 0 radians and progresses around the loop back to theta = 0 radians to begin a new loop. Rules were constructed around what the theta progression should fit. Clearly, some loops shown (Left) did not fit the expected progression and were removed (Right).

Supplementary Fig 2. Raw pressure-volume (PV) loops (blue) with an interpolated PV loop (red) representing the average physiology across numerous cardiac cycles, plotted in polar coordinates. These data are also shown in Fig 2 as Cartesian coordinates.

Supplementary Fig 3. Determination of left upper and right lower corner points algorithmically. A, An example pressure-volume (PV) loop (red line) with points in the left upper segment (blue box) of the PV loop identified (black line). Arrows represent distances from the center point to the points along the line. The blue target represents the point on the line that is the greatest Euclidean distance from the center point, which is not precisely in the true corner. B, Curves representing end-systolic PV relationship (ESPVR) and end-diastolic PV relationship (EDPVR) drawn through the computed corner point with corner point detection via tangent computation.