Use of a conductance (volume) catheter and transient inferior vena caval occlusion for rapid determination of pressure‐volume relationships in man

Determination of left ventricular pressure‐volume relationships in situ ideally requires both a method for easy measurement of multiple pressure‐volume loops and a rapid and reversible means of altering load. We report a technique, previously used in animals, that combines conductance catheter volumes and rapid inferior vena caval occlusion to permit routine measurement of calibrated P‐V relationships in man for the first time. An 8F volume catheter with a 3F micromanometer tipped pressure catheter placed through its lumen was advanced to the left ventricular apex through a femoral artery. A thermodilution output catheter was placed through a 9F femoral venous sheath and later replaced with an IVC balloon occlusion catheter, through which a 2.5F bipolar wire was advanced for atrial pacing. A specialized data system facilitated collection, editing, and data analysis at the time of cardiac catheterization. Absolute volume calibration required cardiac output measurement and injection of hypertonic saline. IVC occlusion decreased peak left ventricular pressure by 42 ± 17 (SD) (P < .001) mm Hg in 15 patients. Endsystolic pressure‐volume relationships (ESPVR) were determined with 5–8 cardiac cycles with an average of r² of 0.94 ± 0.05 and were generally reproducible. The slope of the ESPVR demonstrated consistency among a group of normal patients (n = 6), and was significantly lower than the slope derived from a group of patients with ventricular hypertrophy (n = 9). We conclude that left ventricular pressure‐volume relationships can be easily and repeatedly determined as part of a routine cardiac catheterization in man.