INCREASED AIRWAY PRESSURE AND SIMULATED BRANCH PULMONARY-ARTERY STENOSIS INCREASE PULMONARY REGURGITATION AFTER REPAIR OF TETRALOGY OF FALLOT - REAL-TIME ANALYSIS WITH A CONDUCTANCE CATHETER TECHNIQUE

Background Pulmonary regurgitation (PR) is an important determinant of outcome after repair of tetralogy of Fallot. Baseline PR was measured by magnetic resonance (MR) phase velocity mapping and from real-time right ventricular pressure-volume loops with a conductance catheter. S ubsequently, the impact of two loading maneuvers (increased airway pre ssure, simulated branch pulmonary artery stenosis) on PR was assessed by the conductance catheter method. Methods and Results Thirteen patie nts, 3 to 35 years after tetralogy of Fallot repair or pulmonary valvo tomy, had PR measured by MR phase velocity mapping while breathing spo ntaneously. During catheterization under general anesthesia, PR was es timated from right ventricular pressure-volume loops generated by cond uctance and microtip pressure catheters. The effect of increased airwa y pressure (continuous positive airway pressure, 20 cm H2O; n=12) and simulated branch pulmonary artery ste stenosis (transient balloon occl usion of a branch pulmonary artery, n=7) was measured. Basal PR fracti on derived by MR and from right ventricular pressure-volume loops had a correlation coefficient of .76 and mean of differences of 2.0+/-18.2 % (95% limits of agreement). Increased airway pressure increased PR (1 6.3+/-11.4% to 25.7+/-17.3%, P<.01). Simulated branch pulmonary artery stenosis increased right ventricular end-systolic pressure (69.1+/-21 .4 to 78.7+/-23.1 mm Hg, P<.05) and PR (27.5+/-11.3% to 36.9+/-12.8%, P<.05). Conclusions There was reasonable agreement between MR phase ve locity-derived PR fraction and that obtained from right ventricular pr essure-volume loops generated by use of conductance and pressure-micro tip catheters. Exacerbation of PR by increased airway pressure and bra nch pulmonary stenosis may be relevant to the acute postoperative and long-term management, respectively, of patients after repair of tetral ogy of Fallot.