Clyman R I, Roman C, Heymann M A, Mauray F
Cardiovascular Research Institute, San Francisco, California.
Pediatr Res. 1987 Nov;22(5):531-5. doi: 10.1203/00006450-198711000-00012.
A model of patent ductus arteriosus in premature lambs was created to examine the lamb's ability to handle the volume load imposed by a patent ductus arteriosus and to determine the lamb's ability to handle any additional volume load. Fifteen preterm lambs [133 +/- 2 (+/- SD) days gestation, term 145 days], whose ductal diameter could be regulated with a mechanical occluder, were studied to determine the independent effects of ductus patency and a saline volume load (50 ml/kg over 3 min) on left ventricular output and its distribution. During a saline infusion, preterm lambs with a closed ductus could only increase their stroke volume by 40% above baseline stroke volume. When challenged with a saline infusion, lambs with an open ductus still were able to increase their stroke volume significantly; the maximal increase in stroke volume during the saline load with the ductus open was 70% above baseline stroke volume. We hypothesize that the associated reduced left ventricular afterload plays a significant role in the preterm lamb's ability to increase its stroke volume when challenged with a patent ductus arteriosus. Even with a patent ductus arteriosus, the lamb still has the ability to handle additional volume loads.
建立早产羔羊动脉导管未闭模型，以研究羔羊应对动脉导管未闭所带来的容量负荷的能力，并确定羔羊应对任何额外容量负荷的能力。对15只早产羔羊[妊娠133±2（±标准差）天，足月为145天]进行研究，其动脉导管直径可用机械封堵器调节，以确定动脉导管通畅和生理盐水容量负荷（3分钟内50毫升/千克）对左心室输出量及其分布的独立影响。在输注生理盐水期间，动脉导管闭合的早产羔羊只能将其每搏输出量比基线每搏输出量增加40%。当受到生理盐水输注挑战时，动脉导管开放的羔羊仍能够显著增加其每搏输出量；动脉导管开放时生理盐水负荷期间每搏输出量的最大增加比基线每搏输出量高70%。我们推测，相关的左心室后负荷降低在早产羔羊受到动脉导管未闭挑战时增加其每搏输出量的能力中起重要作用。即使存在动脉导管未闭，羔羊仍有能力应对额外的容量负荷。
