肺動脈狭窄症の右室機能に関する研究

Right ventricular volume characteristics and function in patients with pulmonary atenosis

　先天性心疾患においては，大血管転位症，ファロー四徴症のチアノーゼ性心疾患を除くと，一般的には右室圧負荷が必ずしも右室のポンプ機能を低下させておらず，右室機能は良好に保たれているものと考えられている^1）。著者らは大血管転位症においては左室／右室収縮期圧比が右室のポンプ機能と密接な関係にあり，これが心室中隔の偏位と関連性のあることを推察して来た^2,3）。この考えを広く応用すると，右室圧が左室圧を凌駕する様な極めて右室圧が高い肺動脈狭窄症においては，右室ポンプ機能は低下しているものと考えられるが，これらを詳細に検討した報告は見当らない。一方，圧負荷は心筋肥大を招き，左室においては拡張期機能が損なわれていると考えられている^4）。そこで，本研究においては心室中隔欠損を合併しない肺動脈狭窄症における右室機能を検索し，圧負荷の右室機能におよぼす影響について検討した。

Right ventricular volume and function were assessed in 16 patients with pulmonary stenosis, Six (mild PS) had right to left ventricular systolic pressure ratio less than 0. 70, four had that betwe-en 0.70 and 1.0 (moderate PS), and six had that more than 1.0 (Severe PS), respectively. Right ventricular end-diastolic pressure averaged 7±2 mmHg in mild PS, 11±5mmHg in moderate PS (p<0.001 vs. normal value), and 11±2 mmHg in severe PS (p<0.001 vs. normal), respectively. Right ventricular end-diastolic volume index ave-raged 83±17ml/m² in mild PS, 72±31ml/m² in moderate PS, and 92±31ml/m² in severe PS, respectively. Right ventricular ejection fraction averaged 0.60±0.08 in mild PS, 0.55±0.06 in moderate PS, and 0. 42±0.08 in severe (p<0.01 vs. normal), respectively. Compliance of the right ventricle averaged 0.10±0.03mmHg^-1 in mild PS, 0.06±0.04mmHg^-1 in moderate PS (p<0.01 vs. normal), and 0.04±0.01mmHg^-1 in severe PS (p<0.001 vs. normal), respectively. There was a high correlation between compliance of the right ventricle and the right to left ventricular systolic pressure ratio (Y=0.17X^-1.19, r=-0.86, p<0.001).

These results demonstrated that right ventricular pump function was depressed significantly in pa-tients with high right ventricular pressure similar to or more than the left ventricular pressure, and right ventricular diastolic function was abnormal in pa-tients with the right ventricular pressure more than one half of the left ventricular pressure.