LEFT-VENTRICULAR SYSTOLIC PERFORMANCE IS DEPRESSED IN CHRONIC PULMONARY-EMPHYSEMA IN DOGS

The effect of chronic right ventricular (RV) pressure overload on left ventricular (LV) systolic function in chronic obstructive lung diseas e is unclear. To examine LV systolic performance in pulmonary emphysem a, a chronic canine model was developed in which pulmonary artery pres sure could be elevated to a level found in human disease. Severe emphy sema was produced by the repeated instillations of the enzyme papain i nto the lung. Sonomicrometry was used to assess LV dimensions along th e septal-lateral, apex-base, and anterior-posterior orthogonal axes of the LV. With the animal conscious, measurements of LV systolic functi on were obtained over a wide range of LV circumferential end-ejection stresses at baseline and after 1 yr of emphysema (post-1-yr study). In the emphysema group (n = 5), the results showed that at the post-1-yr study, measurements of LV ejection fraction, mean velocity of circumf erential shortening, and rate of anterior-posterior dimensional shorte ning were reduced compared with those obtained at the baseline study. In the emphysema group, end-systolic volume was increased for a given end-systolic pressure or stress at the post-1-yr study compared with b aseline values, while fractional shortening measured along the three a xes was decreased. There were no similar changes in systolic parameter s in control groups. We conclude that chronic RV pressure overload may cause an impairment in LV systolic performance in chronic emphysema.