Difference in Right Ventricular Function between Post-tuberculosis Emphysema and Primary Emphysema

Kim, Myung A; Kim, Sang Hyun; Chung, Hee Soon

Abstract

BACKGROUND
Tuberculosis itself causes not only lung parenchymal destruction but also pulmonary vascular damage. Secondary emphysema also causes pulmonary vascular damage, which can develop as a late sequela of pulmonary tuberculosis. Therefore, pulmonary circulatory impairment tends to be more severe in post-tuberculosis emphysema than in primary emphysema. In post-tuberculosis emphysema, the right ventricular function may play an important role. However, little information regarding the right ventricular function is available. The purpose of this study was to evaluate and compare the right ventricular function between post-tuberculosis emphysema and primary emphysema. METHOD: Post-tuberculosis emphysema(PTE) or primary emphysema(PE) was diagnosed by history, HRCT finding and pulmonary function. Twenty patients with post-tuberculosis emphysema were matched with 20 patients with primary emphysema according to both FEV1 and FVC. Arterial blood gas analysis and echocardiography were done at rest and immediately after symptom-limited exercise. The right ventricular function was evaluated with the right ventricular ejection fraction using a modification of Simpson's method.
RESULTS
There was no significant difference inthe demographics and pulmonary function between the two groups. In post-tuberculosis emphysema, the PaCO2 was higher (42.9±4.7 vs 38.8±3.1 mmHg at rest ; 47.9±7.0 vs 41.1±5.9 mmHg after exercise ; p<0.01) and the right ventricular ejection fraction was lower (57.6±6.5 vs 61.4±4.7 % at rest ; 51.1±10.8 vs 59.8±6.6 % after exercise ; p<0.01) both at rest and after exercise. The PaO2 after exercise was also lower (65.7±12.6 vs 80.2%±14.4 mmHg, p<0.01), while the PaO2 at rest tended to be lower(82.9±12.0 vs 87.8±7.5, p>0.05). In both groups, right ventricular ejection fraction correlated with the PaO2 after exercise(PTE r=0.536, PE r=0.557), and the PaCO2 at rest(PTE r=-0.576, PE r=-0.588) and after exercise(PTE r=-0.764, PE r=-0.619).
CONCLUSION
Impairment of the right heart function and gas exchange were more serious in post-tuberculosis emphysema than in primary emphysema, and gas exchange may be influenced by the right ventricular function in post-tuberculosis emphysema.