肺血管床を介しての拡張期圧較差—とくに各種心疾患の肺血管抵抗に関する考察

A Study on Diastolic Pressure Difference across the Pulmonary Vascular Bed:with Special Refference to the Pulmonary Vascular Resistance in Heart Diseases

はじめに

　肺動脈拡張終期圧は，肺血管障害のない場合，十分に拡張期が長ければ，左房圧，ないしは左室拡張終期圧にほとんど一致し，両者間に圧較差がないことは知られており^1），心不全時の運動負荷，ジギタリス負荷などの研究のさいにも，左室拡張終期圧の指標として，肺動脈拡張終期圧を用いた報告がある^2）〜4）。

　一方，肺血管障害をきたす肺高血圧症のある例においては，肺動脈拡張終期圧と，左房または左室拡張終期圧との間に較差をみとめることが多い。

　最近発達した電磁流量計による開胸犬の肺動脈主幹の血流波形の記録よりみると，少なくとも右心一回拍出量のほとんどは，収縮期に流れ，肺血管全体としての拡張期の血流は肺血管の弾性により一時プールされた血流がよりおそい速度で左心系に流れこむものと考えられる。拡張終期の肺動脈・左房の圧較差は，定常流に近い状態での圧差ということができ，正常肺血管では，この圧差がほとんどゼロであることを考え合わすとき，この圧差は肺血管抵抗の一つの指標となりうるものと思う。

　本研究は，心疾患における肺高血圧症を，肺動脈・左房間の拡張終期圧較差から，肺血管抵抗について検討したものである。

One hundred and sixty patients with cong-enital or acquired heart disease were subjec-ted to right and trans-septal left heart catheterization.

The main purpose of this presentation was to study the pressure difference between diastolic pulmonary arterial pressure (PADP) and left atrial mean pressure (LAMP), which can be regarded as an index of pulmonary vascular resistance.

1. The study of the PADP-LAMP gradient in atrial fibrillation revealed that heart rate was not a factor in the genesis of the diffe-rence, unless heart rate was over 120 per minute.

The heart rate of all patients in this study ranged between 52 and 130 per minute (ave-rage: 86 per minute).

Therefore, the effect of heart rate was not taken into consideration in this study.

2. The PADP-LAMP difference was line-arly correlated with PADP (r=0.68).

This linear correlation suggests that PADP does not quantitatively mirror LAMP and that there must be some mechanism which promote a rise in pulmonary resistance.

3. In cases with P. V. R. below 250 dynes sec/cm⁵, the PADP-LAMP difference is sta-tistically constant (PADP-LAMP=1.7mmHg), whereas in cases with P. V. R. over 250 dynes sec/cm⁵, the pressure difference tends to increase with P. V. R. (r=0.81). The pulmo-nary blood flow or volume in diastole might be involved in the genesis of the pressure difference across the pulmonary vascular bed, only when the calculated pulmonary vascular resistance is over 250dynes sec/cm⁵.

4. In cases with PADP below 25 mmHg, PADP-PCWP difference tends to increase parallel with PADP, whereas no further increase in the pressure difference is seen in many cases with PADP over 25 mmHg.