REDUCTION OF MISMATCH OF GLOBAL VENTILATION AND PERFUSION ON EXERCISEIS RELATED TO EXERCISE CAPACITY IN CHRONIC HEART-FAILURE

Background-The inability to match lung perfusion to ventilation becaus e of a reduced cardiac output on exercise contributes to reduced exerc ise capacity in chronic heart failure. Objective-To quantify ventilati on to perfusion matching at rest and at peak exercise in patients with chronic heart failure and relate this to haemodynamic and ventilatory variables of exercise capacity. Design-Eight men in New York Heart As sociation class II underwent maximal bicycle ergometry with expired ga s Main outcome measures-On separate days, ventilation and perfusion ga mma camera imaging was performed at rest, and at 80% of previous peak exercise heart rate during bicycle ergometry. The vertical distributio n of mismatch between ventilation and perfusion (V/Q) was estimated fr om subtracted profiles of activity (ventilation and perfusion) to deri ve a numerical index of global mismatch. Results-Maximal mean (SD) oxy gen consumption on bicycle ergometry was 16.0 (4.5) ml min-1 kg-1. The re was a reduction in the global V/Q mismatch index from 23-96 (5.90) to 14.88 (7.90) units (p < 0-01) at rest and at peak exercise. Global V/Q mismatch index at peak exercise correlated negatively with maximal minute ventilation (R = -0.90, p < 0-01) and with maximal mean arteri al pressure (R = -0.79, p < 0-05), although no relation was seen with maximal oxygen consumption. The reduction in global V/Q mismatch index from rest to peak exercise correlated with maximal oxygen consumption (R = 0.88, p < 0-01), and with maximal minute ventilation (R = 0-87, p < 0-01). Conclusions-During exercise in patients with chronic heart failure, there is a reduction in the global V/Q mismatch index. A lowe r global V/Q mismatch index at peak exercise is associated with higher maximal ventilation. The reduction in global V/Q mismatch index on ex ercise correlates well with maximal exercise capacity. This may imply that the inability to perfuse adequately all regions of lung on exerci se and match this to ventilation is a factor determining exercise capa city in chronic heart failure.