Babb J D, Waldhausen J A, Zelis R
Circ Res. 1977 Apr;40(4):372-9. doi: 10.1161/01.res.40.4.372.
Current management of ventricular septal defect (VSD) after myocardial infarction (MI) is aimed at improving left ventricular (LV) performance by afterload reduction as a means of hemodynamic stabilization or shunt control. The current investigation was undertaken to determine whether primary manipulation of right venticular (RV) performance by afterload enhancement was an effective means of reducing MI-VSD shunting. In five open-chest dogs an external LV-RV shunt was created with pulmonary-systemic flow ratios (Qp/Qs) averaging 2.26:1. Inflation of a balloon-tipped catheter in the main pulmonary artery (PA) reduced average QP/Qs to 1.28:1 and shunt flow from 783 to 343 ml/min. However, this increase in RV afterload caused further significant increases in RV systolic and end-diastolic pressure and suggested that deterioration of RV function might be limiting the usefulness of this technique. To investigate whether inotropic support for the RV would overcome this limitation, a similar shunt was created in 11 open-chest swine. We then investigated the effects of dopamine, infused at 24, 60, and 120 mug/min, on QP/QS and other hemodynamic variables both with and without PA balloon inflation. Optimal shunt control was obtained when effects of dopamine were added to those of PA balloon inflation. Shunt flow that had been 1,633 ml/min was reduced to 892 ml/min with the PA balloon and reduced further to 757 ml/min with dopamine, which also lowered RV and LV end-diastolic pressure and reduced total systemic vascular resistance. In four other swine with left anterior descending ligations, PA balloon inflation and dopamine infusion again favorably affected hemodynamics. Epicardial mapping in these swine showed an increase in S-T segment displacement, suggesting that the cumulative effect of these interventions allowed hemodynamic improvement at the expense of enhanced ischemic injury. These data indicate that acute RV outflow obstruction with a balloon catheter is an effective means of temporarily reducing acute ventricular shunting and that dopamine may be a useful pharmacological agent to use with RV afterload manipulation to stabilize a patient prior to transfer to a medical center for more definitive therapy.
心肌梗死（MI）后室间隔缺损（VSD）的当前管理旨在通过降低后负荷来改善左心室（LV）功能，以此作为血流动力学稳定或分流控制的手段。当前的研究旨在确定通过增加后负荷对右心室（RV）功能进行初步调控是否是减少MI-VSD分流的有效方法。在5只开胸犬中建立了左心室-右心室外部分流，肺循环与体循环血流量之比（Qp/Qs）平均为2.26:1。将带气囊导管插入主肺动脉（PA）并充气后，平均Qp/Qs降至1.28:1，分流血流量从783毫升/分钟降至343毫升/分钟。然而，右心室后负荷的增加导致右心室收缩压和舒张末期压力进一步显著升高，这表明右心室功能恶化可能限制了该技术的有效性。为了研究右心室的正性肌力支持是否能克服这一限制，在11只开胸猪中建立了类似的分流。然后，我们研究了分别以24、60和120微克/分钟的速度输注多巴胺，在肺动脉气囊充气和未充气的情况下对Qp/Qs和其他血流动力学变量的影响。当多巴胺的作用与肺动脉气囊充气的作用相结合时，获得了最佳的分流控制效果。肺动脉气囊充气时，分流血流量从1633毫升/分钟降至892毫升/分钟，使用多巴胺后进一步降至757毫升/分钟，同时还降低了右心室和左心室舒张末期压力，并降低了总体循环血管阻力。在另外4只左前降支结扎的猪中，肺动脉气囊充气和多巴胺输注再次对血流动力学产生了有利影响。这些猪的心外膜标测显示ST段移位增加，这表明这些干预措施的累积效应是以加重缺血性损伤为代价实现了血流动力学改善。这些数据表明，用气囊导管进行急性右心室流出道梗阻是暂时减少急性心室分流的有效方法，并且多巴胺可能是一种有用的药物，可与右心室后负荷调控联合使用，以便在将患者转运至医疗中心进行更确切治疗之前使其病情稳定。
